When reading this article, I highly suggest keeping the Gatecrash Card Image Gallery (or "Visual Spoiler") open in another browser tap for quick reference; I will assume that you have access to this page and will not spell out the text of the cards I mention more than is needed for the purposes of context. Be advised that the article is almost 10,000 words; if you're in a hurry, use the bolded headers to find the parts that are likely to be of interest to you.
Starting Somewhere - The Prerelease Promos
The first cards I want to touch briefly on before we dive into colors or guild color pairs are the prerelease promotional cards which you are allowed to play with during this event. They are all rare cards and yours depends on what guild you pick to represent at the prerelease. In evaluating these cards (and later, the rest of the set), I am making some basic assumptions about the guilds based on their general look and what we know about them; for instance, Boros' primary strategy is a fast, aggressive rush with hordes of small creatures. This is going to color the evaluation of cards somewhat (as it should), but I will do my best to point out whenever a statement hinges on such an assumption.
As an example, let us start with the Boros prerelease promo, Foundry Champion. This card looks pretty powerful on the surface; a 4/4 for six mana that most likely kills a creature or burns your opponent out is a pretty good creature. I think this creature is going to be weaker than it looks, though, because of Boros' speed, but it is a great card to have in any non-optimal Boros pool because it is a great way to close out a game if it should stall out or your offense stumbles a little too early, leaving you with some aggressive creatures but no profitable attack. Taking into consideration the slightly slower nature of Sealed ordinarily, I can't see cutting the card from any but the most streamlined and aggressive Boros decks, and it is a fine splash if the rest of your pool leans you more towards an Orzhov deck.
Speaking of Orzhov... Treasury Thrull is another prerelease card sitting at a 4/4 for six mana, but this in a guild which appreciates it more and with abilities that (at least given time) will be more powerful than the Foundry Champion, I think this card is much more desirable. If it ever survives its first attack, you should almost always be able to lock down the game (get back a spell, cast it, extort). Having this as a guaranteed card in your pool means you will need fewer other curve-toppers to build your defensive, grindy Orzhov deck around. Another card which is great without being overpowering, I can't see cutting the Thrull in an Orzhov pool, and it looks like it would be a decent splash in both of the neighboring guilds (except a lightning-fast, streamlined Boros deck).
Next up is perhaps the audience favorite: The Simic Fathom Mage. At four mana, this card is much more likely to see play every game you draw it, but its immediate impact is also almost non-existent. It is going to be great in almost all opening hands and while the board is still developing, and extra cards never hurts if you are in the process of putting a game away already, but the card is significantly less exciting if you draw it when you are already on the back foot and under pressure. Basically all Simic decks will have enough tricks to do with this card and +1/+1 counters that cutting it would be ridiculous, but it might not quite carry its weight in what I imagine will be a creature-light Dimir deck with plenty of other ways to get ahead in the late-game. The high creature-density in Gruul makes the Mage a reasonable splash there if you can support it.
The Gruul prerelease card, Rubblehulk, is the one I am most in doubt about. The Gruul deck looks aggressive, yet much more midrange-y than Boros, and a 6/6 for six mana with the potential to grow further is not too shabby in that case. The drastic impact of the Bloodrush ability on this card combined with the fact that all Gruul players will have (at least) one copy of the card has radical implications for how you should play both as and against Gruul at the prerelease, though: If a game ever draws long against a Gruul player, be sure not to let in any attackers unblocked that would not instantly kill you if your opponent has Rubblehulk; if you are the person playing Gruul, be sure to both play out all your lands and to be aware of the opportunity to force bad blocks like these when you, in reality, have another trick or bloodrush creature in hand. This advice goes mostly towards playing against other skilled players; against more unskilled players, make sure not to make bad attacks: new players tend to block too much rather than too little. The card is an excellent splash in both of the guilds it shares a color with; it is almost guaranteed to evolve everything Simic has in play (if it does not lock away the game in the air), and simply outnumbering your opponent as Boros will often be lethal with this trick up your sleeve on the sixth or so turn.
The final prerelease card might look like the least exciting, and I do think its guild - Dimir - is going to be one of the hardest to wrap your head around in limited, but I look at this card in much the same way as I do Treasury Thrull (albeit less useful outside its "main" guild): It is a way for a slow, defensive deck to close out the game. Whether your Dimir deck ends up counting on mill, damage or a mix as its win condition, Consuming Aberration is going to bring you steadily closer to that goal, taking progressively larger chunks out of your opponent's resources the longer they let it live. It can quickly grow to demand an answer in a very short timeframe (while growing whenever an opponent has to "chump-block" it), and you need not invest further resources into it as a threat that can already turn around a game on its own. If your opponent ultimately is able to deal with the card, you should still be left in an advantageous situation. This card is probably the hardest splash to justify in neighboring guilds, especially Simic, and you should be aware of its slow speed and consider including cards adapt at supporting it if you do side with the Dimir at your prerelease. While not being able to cast it on turn five because an opponent has no cards in their graveyard is probably going to be unlikely, it is not impossible if you randomly include this card in a deck that otherwise does not care for such things.
Less Gold Symbols, More Guild Symbols: The Multicolored Commons and Uncommons
Going through the guilds a second time, this one focusing on what will be the bread and butter as well as the top performers of each of the decks with reasonable frequency, let's have another look at the multicolored cards of the set, against starting out with the Boros Legion, the fastest and most aggressive of the guilds. Keeping the guild mechanics in mind during this run-down is a priority.
Right out of the gate (see what I did there?), Boros Charm is a very powerful card (its constructed implications should be the topic of another article): It allows an all-out attack punishing "under-blocking" (with its first ability) or "over-blocking" (with the second). The third ability should seldom be relevant but if your Foundry Champion happens to go unblocked with all your seven mana up... It could be worth more than four additional damage. It is also a fine combat trick (though so is the second ability).
Another cheap trick which can reward you for outnumbering the opponent in the early game is Martial Glory, which will allow a creature to survive combat while getting in more damage with another creature (or allow one creature to "trade up" while avoiding that another one "trades down"). A card I am very excited about is the reprinted Skyknight Legionnaire which allows you to enable Battalion on turn three (if you have been making your one- and two-drops) while being an evasive beater by itself. When I first saw it spoiled, I assumed it would be uncommon, and while the three-drop spot in Boros might turn out to be crucial enough that it has some competition, I think Legionnaire will prove its mettle. The (Sunhome) Guildmage on the other hand will be weaker than it looks, I think. The first ability will probably only serve to get through a few more damage or help creatures trade up, and the second ability is too slow for "Plan A". He is an excellent "Plan B" all by himself, though, and the threat of activation on the first ability is going to have your opponent thinking twice about blocks - or be punished for it.
Talking of "threat of activation", Truefire Paladin is a very scary card which will most likely dominate most battlefields it hits: fearlessly attacking in for two (or six) while keeping the same combat expert back on defense is going to drive your opponent up against the wall fast. Wojek Halberdiers is another great two-drop which really appreciates the turn three Battalion that Skyknight Legionnaire can enable.
The cards to be wary of in the Boros colors are the costier uncommons such as Ordruun Veteran or Fortress Cyclops, which are unlikely to aid your primary plan of early aggression while simultaneously not being very powerful outside of it (the Cyclops being better on its own but much worse as a last inclusion in an aggressive deck). Boros with its focus on speed is also going to be the deck which appreciates the mana-fixing of Gates (probably worth cutting unless your color requirements are tough) and Keyrunes (probably downright unplayable). Indeed, these cards as well as a few of the other larger creatures in Boros colors are probably meant for a slower deck like Orzhov splashing red.
Continuing to Orzhov again, you will probably be planning to drain your opponent out slowly through a long game; this does not mean, however, that you can (or want to) ignore the early game; surviving against aggressive decks is obviously crucial, but getting those 4-8 early damage against decks like slower Simic ones or Dimir durdle-decks means that they will have several turns less to assemble what will often be a superior, over-the-top lategame. For this reason, cards like Cartel Aristocrat (an early bear which can, in a pinch, become evasive in the lategame) should not be shunned although they are obviously not the reason you play Orzhov. Cheap spells are also very synergistic with Extort, obviously. Cards like Kingpin's Pet support this "aggressive Orzhov" strategy well, while removal such as Executioner's Swing and One Thousand Lashes ranges from necessary tools to crucial answers in a game which will probably see your opponent draw a good part of his threats. Cards like Purge the Profane and Vizkopa Confessor are probably still as mediocre as they look, but when your plan revolves around slowly taking away the options of an opponent, they could fit that plan perfectly well in the absence of stronger cards. The Orzhov Charm is fine although it will almost always be a Vendetta, but the Guildmage on the other hand strikes me as very powerful. In a game that goes long, it can transform any innocuous attacker into a significant life-swing and ramp up the speed at which your extortions lock the game away. In its hybrid cards, Orzhov has a fine sideboard tool against Dimir shenanigans as well as an aura that (especially with the Guildmage) can bring you quickly out of range and towards a victory once you have stabilized. Orzhov is probably also going to be the guild which appreciates its own Keyrune the most, being somewhat mana-hungry and able to squeeze value out of the proposition of paying effectively three mana a turn to get a blocker and a single point of life.
The Simic multi-color cards give the impression of a deck which starts slow, establishes a solid presence midgame which threatens to overflow into perhaps the most powerful endgame in the environment (akin to the Selesnya tokens deck once it got "out of control"). In order to properly take advantage of this capacity, though, the cards that you play in the first several turns of the game must be able to protect you - preferably while having the guild keyword so they can in time develop into scary threats themselves. This makes me think that cards like Drakewing Krasis and Merfolk of the Depths are worse than they look (the Krasis in particular looks exciting in isolation) - these may be cards aimed at a faster evolve-centric deck which is far more plausible in draft than in sealed even with the addition of the guild booster. On the other hand, cards like Elusive Krasis and Shambleshark are ways of protecting yourself in the early game without losing any late-game power. The Simic Charm looks strong in limited, too, providing a great combat trick, a great tempo play (especially in response to Bloodrush) and a way to protect your powerful creatures against removal. The Guildmage goes right ahead and tops that, sporting two cheap abilities that will make evolve creatures - especially the cheap ones - a lot more powerful. This as well as the hybrid common, Bioshift, makes even more sense together with the prerelease card. I don't think I'm alone in being attracted to Urban Evolution either, a card I could definitely see running in a Simic Sealed pool even if it might be too slow once the time comes around for drafting. Despite this planning for the long game, I don't see a lot of utility in Simic's Gate or Keyrune outside enabling a splash or easing the color requirement of your main colors to allow an easier splash of another color.
Gruul looks much more interesting than Boros to me, despite both of the decks being focused very much towards aggression. It is my impression that a Gruul deck has a much better shot at remaining competitive as the game goes long (without relying on a powerful rare, at least) while still being able to apply early pressure. Gruul also infuses the creature-heavy color of green with much-needed removal from its red side; cards like Ground Assault and what I imagine to be a linchpin of the guild, Pit Fight makes it able to deal with even relatively large creatures. I want to touch on Pit Fight briefly; a good Gruul deck will be playing far more than the standard 15 creatures, making up for the lack of spells with the trick-like application of Bloodrush creatures. Pit Fight's interaction with Bloodrush is very positive; if an opponent has left a single, obstinate blocker back, you can attack with your entire team, pump your biggest guy and then fight the not-yet-blocking obstacle to get it out of the way and get damage in there. While this (and bloodrush in general) is very fragile to disruption and should only be done against someone who's tapped out or out of gas, it can easily be a winning move.
Gruul Charm provides another way to get through on the offense, and with plenty of "fat" like Zhur-Taa Swines and Ghor-Clan Rampager (how is that only uncommon?), that will be a very welcome addition. While Gruul also appear to have the most "dead" cards (Frenzied Tilling and Primal Visitation both look very unattractive if not downright unplayable), the general creature density should make up for that somewhat. An interesting thing to observe will be how aggressively Gruul players will (think they) need to use Bloodrush; I am leaning towards playing the creatures out far more often than using them for short-term gain unless the situation is dire and simply overwhelm my opponent, but some creatures obviously have more desirable bloodrush effects than others (Rubblehulk being the showcase). The Gruul Guildmage's first ability does a lot towards making Bloodrush a more profitable proposition (getting some damage through in addition to eating a blocker), whereas the second one can reward you for having traded aggressively throughout the early turns by quickly overpowering an opponent if the board is somewhat empty. The trample ability as well as the aim towards the midgame might also make the Gruul Keyrune less unattractive, although I am still not terribly excited by it - or keyrunes in general.
Once again, the final guild we deal with is the Dimir which looks most set on a controlling, long-game plan of all the guilds; if you manage to lock a game away with an evasive threat and a cipher spell on their own, it is going to be a freak occurrence. When playing Dimir, it is my suggestion to always plan for the long game. Luckily, there are plenty of tools both in blue and black as well as in their golden cross-section that help you survive to the late-game and get ahead. Bane Alley Broker looks like a great looter which can help you find the cards to live through the early game without permanently abandoning the cards you throw away (as long as the Broker stays alive), and has a reasonable blocking body in a pinch to boot. Mortus Strider is another card which can hold the line, though its mana intensity makes it better later in the game. A little incidental milling makes both the prerelease card and the Guildmage a lot better; the guildmage is a slow but inevitable victory condition once the game is firmly under your control, a role that the uncommon Call of the Nightwing can also be. The Dimir Charm can function as a great defensive removal spell early on or ensure one more turn where your opponent draws nothing useful later, letting your stranglehold slowly increase in strength, whereas cards like Coerced Confession and Dinrova Horror can really swing the game in your favor in the late-game. The hybrid Deathcult Rogue is an interesting card which can combine with almost any cipher spell to put the opponent in a bad spot, though it might need to bite the bullet and go on blocking duty in some games; that's okay, in Dimir, you should be able to find another way to eke out that advantage once you have established dominance in the game. The Keyrune seems like a clunkier (but also more resilient) way to have access to an evasive creature (and cipher works well with it), which makes me think this might be a Keyrune you actually, actively will want in some decks.
Another Wall of Text: Monocolored Commons and Uncommons: How Good - and Where?
A huge chunk of the set will obviously be made up of the monocolored cards, too, and most of these will be better in one guild than in the other(s). I will try to keep this short, but I want to take a look at what I expect to be some of the defining (read: not necessarily "best") cards and the ones whose value changes the most between guilds. Let's not waste any more time and get started with White!
Angelic Edict looks like a great removal spell, much better in Sealed than in Draft for both of the white guilds; Boros will probably be less consistent and will appreciate a way to clear out a troublesome blocker or opposing bomb, whereas the slower Sealed format will allow Orzhov the time to actually cast this later when it has a better target and they have mana for extortions. I would not be averse to splashing this in a Dimir Sealed deck, and even a Gruul deck might appreciate it if they are already playing a few white sources. Assault Griffin is known to be the defining aggressive flier in many core set "skies" decks, and while I think the evasion is still going to mean that this card is strong, it fits less well into both Boros and Orzhov than I would like (without being "bad" in any of those decks). Basilica Guards and Boros Elite are obviously very much only for their own guilds (and very bad in the other's), and the same goes for Daring Skyjek and Dutiful Thrull (both look solid in their own guilds if unimpressive in the other's). Guardian of the Gateless is a surprisingly powerful card for an uncommon, mostly in Orzhov but large evasive threats are welcome everywhere, and Knight of Obligation and Holy Mantle are probably really powerful in both white guilds.
On the other hand, cards like Knight Watch, Murder Investigation and Nav Squad Commandos look like cards that I would be hoping not to play even in my Boros deck, although they should all be playable if your deck needs a little gas in the late-game. Smite and Shielded Passage are both great defensive spells in an Orzhov deck; cheap enough to easily extort (or just "camouflage" them in a non-optimal curve-out), and Passage could be an okay trick to enable an otherwise unprofitable Battalion attack in Boros. Syndic of Tithes might have an Orzhov watermark, but could easily slot into a Boros deck's curve. The color ends with two very interesting cards, Urbis Protector (probably playable if unexciting - if you can't return it to your hand to recast it) and Zarichi Tiger (a body too unimpressive and slow for the Boros, but a fine addition to an Orzhov deck that looks to get out of range once the board is stabilized - while not being that bad of a blocker when it comes down. Players who underestimate repeatable lifegain will dislike this card, but Healer of the Pride proved its mettle in M13 and this cat probably won't do a lot worse).
Blue has some great defensive cards such as Aetherize (fine to reset a Boros battalion for some tempo but better against a Gruul bloodrush - and ultimately going to be at its best against Selesnya tokens in the full block format) and Agoraphobia (which is also a great tool to trigger your evolving creatures in a late-game stall) as well as Clinging Anemones, whose cost is probably a mana too high to be really useful but which can scale throughout the game to block everything on the ground - and get rid of quite a lot of it. Frilled Oculus looks like it belongs in this camp, too, and I would be fine playing it as a blocker even without access to green mana in Dimir, but in Simic it can also go on the offensive. Cloudfin Raptor will be a great centerpiece in the aggressive evolve-centric decks much more likely to come together in draft - a deck which will also have a much better application for Gridlock than most of the blue sealed decks (though splashing this in Gruul is my no means out of the question). Incursion Specialist is another great card for Dimir decks that want to block early on and then turn around and find a way to win the game later on, though its ability is quite the non-bo with Cipher.
The effect on Keymaster Rogue is interesting, especially in Simic (returning your Fathom mage - after drawing the card of course - is a great use), but will depend on the particulars of your deck. Generally speaking, I am willing to grant cards with potential like this a little more credit than they might deserve - Leyline Phantom is another such card, though its utility in evolving your creatures is even more obvious. Mindeye Drake is so much more than Rotcrown Ghoul ever was, and Rapid Hybridization is a fine answer to an enemy bomb (or their removal) while also being able to evolve your own creatures in a pinch. Simic Fluxmage and Sapphire Drake are both great when the game goes long - obviously much more so together(!), in Dimir but especially in Simic. Skygames might actually be worth it (but probably isn't), and Totally Lost is another great reply to a Bloodrush activation. Voidwalk looks bad, though if you can connect reliably, you could set back a Simic player's progress a lot or squeeze some value out of the otherwise unexciting Sage's Row Denizen. Way of the Thief looks like a Dimir card but might actually be best in Simic or even in a splash of a Gruul deck.
Black as the other half of the Dimir colors also provide some solid removal options; the stats on Balustrade Spy are perfectly fine for him to not even have the milling ability (which will just be random value in a Dimir deck), and Basilica Screecher brings back fond memories of treating an opponent to the "death of a thousand needles" that Orzhov administered in the original Ravnica block with cards like Mourning Thrull, though encoding a spell on this evasive two-drop and then getting to cast the copy (and extort) also sounds like a delicious proposition that few Dimir mages could resist. Corpse Blockade is a fine blocker as-is and its activated ability provides an intimidating proposition for anyone who wants to attack into it (sacrificing another creature that was chump-blocking something large sounds reasonable), and Death's Approach, Devour Flesh, Grisly Spectacle and Killing Glare provide a great suite of removal at low rarity (most of it at a cost that will allow you to extort, too), what looks to be a great boon to the black guilds. Dying Wish and Gateway Shade strike me as mediocre at best, although there is something to be said for giving your opponent a hard choice by encoding onto a creature you can pump infinitely.
Horror of the Dim does not look impressive, and Illness in the Ranks is obviously not meant primarily for limited, though it could be a solid sideboard card against some Boros cards that are hard to handle otherwise. Gutter Skulk is another black bear, probably not what any of the two black guilds want, although it is a reasonably effective creature on both offense and defense in the first turns of the game. Shadow Alley Denizen and Slate Street Ruffian do not look like they fit well into the black guilds, and Shadow Slice is probably not going to be very good either although it can quickly close out a game where you're already attacking in the air. Syndicate Enforcer and Thrull Parasite ask interesting questions about the value of extort but are probably generally worth running (if unexciting), though I could easily see taking them out against aggressive decks. Undercity Informer is a reasonable blocker that can help you move all in on a milling plan in the late-game if needed (probably only viable in some Dimir decks), and Smog Elemental is a fine curve-topper for a black deck which needs a victory condition at any cost or wants to be even more untouchable (in the air, namely). Wight of Precinct Six is an interesting card and one I will give the benefit of doubt - for the moment. It could get out of control but is obviously not worth a lot in the early game.
Red opens up just like in Return to Ravnica, with a reprinted threaten-effect, this time around it's Act of Treason, and it is going to be just as scary (if not scarier) than Traitorous Instinct was in Rakdos or Izzet decks... It removes a blocker while simultaneously easing the enabling of Battalion. You'd do right to be afraid of this card out of a Boros opponent. Bombardier Corps is a card I am much less convinced about. The ability is powerful, but there are some hoops to jump through, and the body it is on is not exciting. I guess it will increase a lot in value in multiples. Cinder Elemental strikes me as a card worth splashing much more than a card for red decks, though removal is removal, I guess. Crackling Perimeter looks silly and will probably not be playable outside the most greedy decks loaded up on gates of all kinds - not a deck that sounds very red. Perhaps in full block. Ember Beast looks unexciting compared to Mogg Flunkies, recent in memory from M13, but in Boros a creature will rarely be attacking alone anyway, and that extra toughness is going to make a difference; this is one of the Boros creatures that might not need assistance to survive combat with other creatures. Firefist Striker is squarely in the other camp; fragile and worth keeping around, risking this guy in combat is not worth it unless you are applying immense pressure right now, because he seriously alters how your opponent plays and what they keep back for blocking. Imagine it with Act of Treason...!
Foundry Street Denizen looks unimpressive (as most 1-drops are bound to), but is probably decent in a very streamlined aggressive Boros deck which really wants Battalion on turn three. Furious Resistance looks like something you don't really want to be doing in red, and you really have to be committed to that aggressive Boros strategy for Hellraiser Goblin to be worth it - though he does enable Battalion on turn three. On the other hand, Homing Lightning is a fine removal spell (with some potential for upside) and Madcap Skills makes a Boros Battalion much harder to block profitably. Mark for Death looks like it has a home in a Grull fatty-strategy where you can tactically take out a blocker, thus weakening your opponent for next turn, and Massive Raid looks like a fine Annihilating Fire replacement, though with a bit of variance thrown in. It nicely reinforced the theme of red guilds, controlled aggression - you do not want to be throwing your creatures away for short-term advantage. Mugging is another solid removal spell which has a late-game application, and Ripscale Predator looks like something Gruul would really appreciate. Scorchwalker on its own looks quite unexciting, but its bloodrush does a great Lava Axe impression if your creatures can outnumber your opponents (do you use it on turn three instead of developing your board? You might, in Boros). Skinbrand Goblin is a fine Goblin Piker that Boros will probably appreciate more than Gruul. Skullcrack is probably only for the most extreme Boros decks, but could be a fine sideboard card against Orzhov decks to keep them within range. Structural Collapse, Tin Street Market and Towering Thunderfist all look very unexciting, though the aura and the creature might be okay for Sealed if not draft. Viashino Shanktail is a great creature or a great trick, although that fourth mana in the cost hurts it somewhat. Finally, Warmind Infantry is another card that might look unexciting but which will probably do well in a Battalion attack and life to tell the tale unless your opponent expends significant resources to deal with it. Toughness is good on attackers, too.
Getting to the home stretch, we have green. This looks to me like a strong if somewhat "dumb" color: lots of creatures, and lots of them are good. Off the bat, we have Adaptive Snapjaw, a creature which might look fragile but which provides a lot of value in evolving your other creatures (and profits nicely from evolving itself) - and with the panic effects and way to grant evasion in the set, there is something to be said for having access to six power on turn five. I know this is outside guild territory, but a Gifts of Orzhova on this one... Ugh! Alpha Authority does not provide a P/T boost, but turns an already large creature into an inevitable killing machine. Slap it on a Ripscale Predator, and fun things will happen... Burst of Strength is a great trick - costing only one mana makes it a lot more interesting than Savage Surge, and the bonus sticks around. Crocanura looks like a creature I would just love to have in my deck (and looks like a great blocker that can play the role of a (Trained Armadon) later on), while Crowned Ceratok is a somewhat aggressively costed creature which will make Simic offenses a lot more intimidating while simultaneously being a great target for Bloodrush tricks. Disciple of the Old Ways looks unexciting at first, and Gruul might not be the guild looking for a bear the most, but its ability is another one which plays well with Bloodrush - and that threat alone should let it pass unblocked at times. Experiment One could get out of control, but I'm not sure I like it enough - Forced Adaption on the other hand seems like a decent aura, especially if you happen to be playing a Fathom Mage...
Greenside Watcher does not look impressive unless you are getting greedy with a Gate-rich mana-base, but Hindervines on the other hand looks like it could be a great blowout in Simic (if you are not up against another Simic!) - it is probably a card you sideboard in, though. Ivy Lane Denizen looks like a powerhouse, and Miming Slime looks like a great follow-up to a Bloodrush-filled combat that succeeded. Naturalize is always a fine card though mostly sideboard material, and Predator's Rapport is probably a huge trap - I don't even think it will make sense against Boros. Rust Scarab has a great size (especially for pumping evolvers) for its cost and the added ability is just gravy. Scab-Clan Charger looks mediocre on the creature side but decent as a combat trick - how nice it is both in one so you don't have to pick. Serene Remembrance is probably a big no-no unless you count on the game going really, really long (out of the board against Dimir, maybe?), Slaughterhorn is effective on both "sides" if not overly exciting and Spire Tracer is probably just unplayable. Tower Defense is a very desperate sideboard card (but don't forget it exists), and I think Verdant Haven might actually be playable - it is acceleration, after all. Wasteland Viper probably impresses me way too much, but I could think of lots of situations where I would appreciate both the creature and the trick, and Wildwood Rebirth is probably actually decent with all the creatures you will be pitching as tricks (or losing in combat) - regrowing one of your most powerful creatures is often worth running this card since it will very rarely be dead even if it is a little clunky.
That concludes our tour of the mono-colored cards. I will touch briefly on a few artifacts before fleshing out my opinions on the looks of the different guilds in a little more detail. Armored Transport seems underwhelming, but probably has some place in Boros Battalion decks, Millennial Gargoyle looks like a very desperate inclusion but you might decide you need it against a solid ground defense in something like Gruul or to prevent a Dimir player from recklessly encoding tons of spells on his tiny fliers and beat you to oblivion. Prophetic Prism is a card I can't evaluate objectively because I like it so much, but it is probably an auto-include whenever you are splashing a third color. Razortip Whip looks unplayable unless your Black deck really, really needs another card that nibbles away at your opponent. Riot Gear and Skyblinder Staff strike me as decidedly unimpressive, but perhaps the +1/+2 is worth it in a deck filled with Boros weenies.
Enough Talking Already: What's the Rundown?
An easily digestible short blurb about each guild is probably very useful if you haven't decided what to play at your prerelease yet (I plan on playing Dimir in the large midnight release and Gruul in a smaller one where I also have to help judging which makes me want to end games a little early - plus combat tricks are always better against less experienced players, especially in a new format). Here's the short version;
Boros wants to be all-out aggressive and very low-curve. You want one-drops that can attack, two-drops that can falter or gain evasion, and three-drops with haste. While you probably have to play a few four- or five-drops, you need to seriously consider what cards to include at higher costs. A deck like this requires some luck in opening to come together in Sealed, but if a lot of your bombs are in Boros, you can aim for a deck that's a little slower, blooding your opponent early so you need very short time to finish them off in the late-game. Boros is the deck I think is going to be the least fun to play at the prerelease (on average), but if you want a better shot at opening Aurelia for a sweet Commander deck (or you are of Boros allegiance), I don't think it's worth staying away from - it by no means looks outright terrible. Notable stronger-than-they-look cards are Daring Skyjek (especially if you have one-drops), Knight of Obligation, Act of Treason, Ember Beast, Firefist Striker, Foundry Street Denizen, Madcap Skills, Massive Raid, Scorchwalker, Skinbrand Goblin, Warmind Infantry, Boros Charm, Martial Glory, Skyknight Legionnaire, Truefire Paladin and Wojek Halberdiers, with Blind Obedience, Frontline Medic, Gideon, Champion of Justice, Legion Loyalist, Assemble the Legion, Aurelia, the Warleader, Aurelia's Fury, Firemane Avenger, Spark Trooper and Boros Reckoner as the most impressive rares. Avoid cards like Basilica Guards, Debtor's Pulpit, Smite, Zarichi Tiger and Mark For Death that go against the game-plan of your deck and be wary of expensive cards like Luminate Primordial, Urbis Protector, Ripscale Predator, Tin Street Market, Towering Thunderfist and Fortress Cyclops whose immediate impact may not be worth the wait.
Orzhov leans towards a controlling game-plan, though enough fliers or a good opening hand can enable you to be slightly more proactive. You want to establish a strong defense while simultaneously setting up a few creatures with Extort to start taking bites out of your opponent's life total as soon as you can afford to. This is a very viable strategy in Sealed, at least if your deck actually has enough of those Extort/evasion creatures to close out a game before an opponent draws their bombs. Orzhov's late-game looks ultimately less overwhelming than both Simic's and Dimir's (and perhaps even Gruul's) in terms of on-board power, so including a few ways to effectively close out a game you are in control of is probably a good idea. As should surprise no-one, those with money on their mind should probably choose Orzhov because of the increased odds of opening Obzedat, a card which is sure to have constructed implications. An Orzhov deck should aim at establishing an early presence while setting up for Extort activations with cards like Basilica Guards, Dutiful Thrull, Knight of Obligation, Syndic of Tithes, Zarichi Tiger, Basilica Screecher, Thrull Parasite, Kingpin's Pet and Vizkopa Guildmage, starting to take control of the game through application of (mostly cheap) removal spells like Angelic Edict, Smite, Death's Approach, Devour Flesh, Grisly Spectacle, Killing Glare, Executioner's Swing and One Thousand Lashes in tandem with Extort triggers, closing out the game with evasive (or just big) threats like Guardian of the Gateless, Urbis Protector, Smog Elemental or well-placed Gift of Orzhova, hopefully supported by rares like Angelic Skirmisher, Luminate Primordial, Lord of the Void, Sepulchral Primordial, Deathpact Angel, Treasury Thrull or Obzedat. Orzhov looks to have fewer dedicated victory condition cards but applying Extort correctly means you will not need as big an advantage as other guilds. Steer clear of cards like Aerial Maneuver, Boros Elite, Court Street Denizen, Daring Skyjek, Knight Watch, Righteous Charge, Shadow Alley Denizen and Merciless Eviction that do not support your strategy in the early nor in the late game.
Simic looks like a guild capable of contending somewhat successfully in the early game but which really wants the game to go longer. The compounding advantage of getting a chain of Evolve going, especially with a powerful card like Fathom Mage or Zameck Guildmage in there is something that will render most opponents utterly unable to compete. The colors have little life-gain, and as such may have to be more aggressive against Orzhov opponents (and perhaps top-tier Dimir ones too), but in a Sealed prerelease you should be planning for the late-game while respecting the early-game threat of the Red guilds. Establishing a defense with potential to adapt to going on the offensive later means running cards like Agoraphobia, Frilled Oculus, Incursion Specialist, Simic Fluxmage, Crocanura, Experiment One, Ivy Lane Denizen, Verdant Haven, Wasteland Viper, Elusive Krasis, Shambleshark and Zameck Guildmage, really empowering your deck later when landing cards like Leyline Phantom, Sapphire Drake, Adaptive Snapjaw, Crowned Ceratok, Rust Scarab, Drakewing Krasis, Nimbus Swimmer or Urban Evolution. Adding some tricky plays like AEtherize, Gridlock, Keymaster Rogue, Alpha Authority, Hindervines, Simic Charm, Bioshift or an instant-speed Evolve support card in Merfolk of the Depths can give you more wiggle room to outplay an opponent, and there's plenty of both power and trickiness in desirable rares like Simic Manipulator, Gyre Sage, Ooze Flux, Sylvan Primordial, Fathom Mage, Master Biomancer, Mystic Genesis, Prime Speaker Zegana and Biomass Mutation. Avoid cards like Hands of Binding, Metropolis Sprite, Scatter Arc, Voidwalk, Disciple of the Old Ways, Serene Remembrance, Spire Tracer, Wildwood Rebirth and Hydroform which does very little for your Evolve development while not being strong enough on their own to make the cut. Also be wary of including too many cards like Cloudfin Raptor (which depends on others before it becomes useful) and Drakewing Krasis (which should rarely be a turn three play despite the mana cost).
Gruul looks like most "dumb" guild to me - which is not to indicate that it is bad, because it looks pretty ruthlessly effective to me. It relies less on weenies than Boros and more on solid, fat creatures - the good old green way. Supported with some red burn, panic effects and other fun shenanigans, Gruul mages are looking to play a very high creature count, including a fair number of Bloodrush creatures to double as tricks. Any noncreature spells must be picked out with great deliberation, and the curve must be crafted so that early threats or defense can be presented while building up to the dropping of a ton of heavyweighters once the midgame rolls around and players stop making every land-drop. This means that you should value cards like Ripscale Predator, Towering Thunderfist, Rust Scarab, Ghor-Clan Rampager, Zhur-Taa Swine and even Ruination Wurm for the late-game while shoring up the early game with creatures like Skinbrand Goblin, Viashino Shanktail, Crocanura, Disciple of the Old Ways, Scab-Clan Charger, Slaughterhorn, Wasteland Viper and Skarrg Guildmage. The noncreature spells that should get priority in your deck would be cards like Homing Lightning, Mark for Death, Mugging, Alpha Authority, Miming Slime, Ground Assault, Gruul Charm and Pit Fight; that is, removal and cards that really press the advantage of having the largest creature around. Don't bother with cards like Burst of Strength, Forced Adaption, Greenside Watcher, Verdant Haven, Wildwood Rebirth, Frenzied Tilling, Primal Visitation or Burning-Tree Emissary unless you are aching for playables or your early game is downright intolerable without them. Cinder Elemental is a good way of including another body while having access to removal, and you will be happy to open any of Hellkite Tyrant, Molten Primordial, Wrecking Ogre, Giant Adephage, Borborygmos, Clan Defiance, Domri Rade, Gruul Ragebeast, Rubblehulk or Rubblebelt Raiders (almost all creatures) to give your late game that extra punch.
If Gruul is the most "simple" guild, Dimir might look to be the most cryptic and hardest to figure out. Dimir decks will make a priority of setting up a position out of danger of losing without taking over the game through a cipher spell on an evasive threat or just a powerful uncommon or rare by itself. The difficult thing for Dimir mages will be including enough victory conditions without taking too many slots from the cards that are to keep them alive until the late-game. Dimir decks will appreciate early defensive cards like Clinging Anemones, Frilled Oculus, Corpse Blockade, Gutter Skulk and Mortus Strider just fine, but it wants cards like Incursion Specialist, Metropolis Sprite, Sage's Row Denizen, Balustrade Spy, Undercity Informer, Wight of Precinct Six, Bane Alley Broker, Dimir Charm, Duskmantle Guildmage, Deathcult Rogue or even Psychic Strike or Horror of the Dim which also have late-game applications and can hopefully tag up with a spell like Hands of Binding, Last Thoughts, Midnight Recovery, Shadow Slice, Call of the Nightwing or Paranoid Delusions to gradually advance your position, backed up by later-game plays like Mindeye Drake, Smog Elemental, Dinrova Horror or Coerced Confession to further increase your edge and limit your opponent's options. Being able to throw powerful rares like Diluvian Primordial, Stolen Identity, Lord of the Void, Ogre Slumlord, Undercity Plague, Consuming Abberation, Duskmantle Seer, Mind Grind, Soul Ransom, Whispering Madness or Nightveil Specter is only going to bring about inevitable victory faster - though not fast enough that your opponent doesn't first get to wriggle a little in their chair as your sinister web of plans tighten around them.
A Few Last Words: Cards for Constructed and Commander
I wanted to list off the cards from the set that I consider most likely to have constructed implications or a role to play in commander decks. Bear in mind that I am no expert at commander nor at older constructed formats. If you're in doubt about whether a card will be worth holding on to, however, I think a second opinion (mine) will be welcomed. Without further ado:
Blind Obedience; could be a useful tool against aggressive decks playing cards like Hellrider, Falkenrath Aristocrat and Thundermaw Hellkite in standard decks, particularly the ones that will be casting spells like Lingering Souls (twice!).
Boros Elite; a possible one-drop in humans, particularly in block or after Innistrad and Champion of the Parish rotates out.
Frontline Medic; a great addition to humans decks, at least, and a solution to cards like Bonfire of the Damned, Rakdos's Return and (Sphinx's Revelation), this is going to be a factor in standard and block.
Gideon, Champion of Justice; while I am not positive that this will have nearly the impact on standard that people seem to think, it is probably going to be awesome in block and in commander, and it might even see fringe application in modern decks like U/W tron (the deck I hope to build) just like the first Gideon did.
Luminate Primordial; this entire cycle seems to be good material for Commander - Swords to Plowshares on a creature (which can be reanimated, flickered, etcetera) for each opponent is no exception to that.
Diluvian Primordial; just like the rest of the cycle, great in Commander. A Spelltwine on drugs and on a stick is another great value proposition when everyone's throwing around Rite of Replication, Time Stretch, etcetera.
Enter the Infinite; apart from the art being gorgeous, I don't personally have a lot of interest in this card, but brewers in both Commander and "real" formats are going to be making an effort to break this. If they do, it'll be good to have lying around, whether you want to trust their crazy plans involving casting a 12-mana spell or just want to cash them out.
Rapid Hybridization; with access to Cyclonic Rift and Azorius Charm, giving your opponent a 3/3 token doesn't seem like that much of a drawback, and being able to cheaply get rid of cards like Olivia Voldaren and Huntmaster of the Fells or even a Rakdos Keyrune which seems to avoid your sorcery-speed Wrath effects against Jund-midrange decks and the like could be worth considering in standard.
Realmwright; this kind of fixing (outside of green, even) could possibly make it, especially if more cards like Liliana of the Dark Realms that care about having lots of a particular basic land see print. It could also enable playing more of the powerful colorless lands of the Innistrad block. It is a long shot, though.
Simic Manipulator; Commander players loyal to Momir Vig's mission are going to love this card.
Stolen Identity; cloning things lots of times is a favorite pastime of Commander players (see: Rite of Replication). I imagine this is no different, especially since getting it on a creature that can hit any player will allow you to legend rule out any other Commander which might be out on the field.
Voidwalk; unlikely, but might make a splash in Commander. Everyone does love Enters-the-Battlefield abilities.
Crypt Ghast; another sure Commander hit, perhaps with "serious" constructed applications too. Having this effect on a creature that can be reanimated makes it easier to access (but also easier to remove), which appeals a lot to Commander players, I've found.
Illness in the Ranks; a role-player (though sideboard only) card in constructed standard and block.
Lord of the Void; another solid Commander hit.
Sepulchral Primordial; like the others, great for Commander.
Thrull Parasite; a possible role-player in standard and block constructed.
Undercity Plague; "Pox" is a somewhat popular archetype. A repeatable, one-sided version of the effect is sure to entice some designers, though whether they are successful in finding an application for it can't be told. Notably, this card is a terrible fun-killer and should not make an impact on Commander.
Hellkite Tyrant; another card with implications for Commander.
Legion Loyalist; with that big a bonus for attacking with three creatures, I can't see this not having an influence somewhere in a constructed format. It is also a great inclusion in any Krenko, Mob Boss Commander decks.
Gyre Sage; whether this actually makes it in block or standard or not, it's raw potential is going to make it an interesting card, and another thing which is popular in Commander is lots of fast mana - especially in green.
Ooze Flux; another card that is sure to have Commander impact and which just might have a place in some crazy concoction in block.
Serene Remembrance; probably not interesting enough to make it, but worth including in your standard deck along with an Elixir of Immortality if you fear being milled out (probably in the sideboard).
Sylvan Primordial; also a Commander card.
Assemble the Legion; sure to make some Commander decks. Double (or, actually, quadruple) the fun with Doubling Season.
Aurelia, The Warleader; definitely Commander material - probably too expensive for constructed, though.
Aurelia's Fury; the set's big hit in terms of constructed impact, this is (at least) going to impact block and standard significantly. Perhaps it is worth trying out in older formats, too.
Biovisionary; this card begs to be broken in some formats. It's not going to be easy (or probably even close to good enough for constructed), but it is still going to cause interest in the card.
Borborygmos Enraged; not something I would find attractive in Commander, but someone else is sure to.
Boros Charm; two abilities with great relevance for the current and future standard environment.
Clan Defiance; might be worth it in some Jund midrange decks in standard (and block), probably also of interesting to Commander players.
Consuming Aberration; a preview card so probably not holding any real value, but interesting in Commander.
Deathpact Angel; a resilient threat and a super-cool design. Probably not with any serious implications for constructed, but I could see it played in Commander too.
Dimir Charm; three fine and different applications means this is most likely going to have a place somewhere.
Domri Rade; the new Baby Jace! Not quite, of course, but with the steady rise of creatures' power level, it is possible to build a serious deck that can take advantage of this (and cast it on turn two).
Duskmantle Seer; Dark Confidant's grandfather enters the scene! While its higher cost probably means it is less playable, that is quite the bar to set for a card. Almost guaranteed to make an impact in both constructed and Commander.
Fathom Mage; definitely Commander material, probably not quite fast enough for constructed.
Firemane Avenger; an off-chance card. Players love throwbacks to stuff like Lightning Helix, and on a reasonably-sized body, this might make some Boros aggro decks.
Ghor-Clan Rampager; 2 mana for +4/+4 and trample is serious business if you can reasonably combine it with double strike as you should be able to in standard in Naya decks. This might be good enough that it's worth trying out and is almost assuredly going to be useful in block, too.
Gruul Charm; wiping the skies clean of Lingering Souls, ensuring an attack on the ground, or... Something which is probably going to be relevant in a yet-unforeseen way, keeping a few of these around is probably a good idea.
Lazav, Dimir Mastermind; another great Commander subject.
Master Biomancer; probably not good enough for constructed, but with a splashy effect that feels right at home in some Commander decks.
Merciless Eviction; probably too expensive for constructed, but the flexibility and finality could get it there. It definitely has a home as a good safety in Commander decks.
Mystic Genesis; another card worth considering for Simic Commanders.
Obzedat, Ghost Council; guaranteed to have constructed implications, and possibly also going to head a few general decks, even if the exile rules are going to be complicated.
Orzhov Charm; that middle ability is probably worth inclusion in some decks on its own, at least at instant speed.
Prime Speaker Zegana; another good contribution to the Commander cardpool.
Signal the Clans; probably not good enough for constructed, but could fall back on its excellent application in Commander.
Soul Ransom; a possible consideration for Grixis control decks, though it is a very specialized tool not very good for the current metagame.
Spark Trooper; Boros aggro is going to be a thing in standard, and following Silverblade Paladin up with this is going to be devastating.
Treasury Thrull; another prerelease card which should find a place in some Commander decks.
Unexpected Results; another fun card to durdle around with in Commander.
Urban Evolution; a possible card in Bant-colored control/ramp decks as they exist now (if they exist once Gatecrash has had its impact) in standard, and a fine card for Commander, too. Copying this with (Riku of Two Reflections) is... Terrifying.
Vizkopa Guildmage; this combines with Exquisite Blood for an infinite combo which will actually be standard-legal and which will certainly make a few Commander decks even if it fails to impact the "serious" formats.
Whispering Madness; repeatable Windfalls are sure to excite the casual crowd of Commander and other multiplayer formats.
Zameck Guildmage; probably only good enough for Simic Commanders.
Biomass Mutation; another card that is probably a perfect fit for some Commander decks but probably doesn't quite make the cut in constructed.
Boros Reckoner; another possible inclusion in Boros aggro decks in constructed.
Immortal Servitude; another card that will get the Commander deckbuilders brewing.
Glaring Spotlight; one of the most controversial cards of the set, probably going to make a splash in constructed as long as Geist of Saint Traft sticks around, and with applications in older formats or at least in Commander.
Illusionist's Bracers; another card that begs to be broken in Commander (and perhaps in other formats, too?).
Thespian's Stage; an interesting card with an unpredictable future. Is it good enough for standard? modern? Block after Dragon's Maze? We'll see.
The "Shock-Lands"; Stomping Ground, Sacred Foundry, Breeding Pool, Godless Shrine and Watery Grave are already staples of Modern and should be in standard too once legal. Hold on to them (except perhaps the Foundry if people are willing to pay overprice on it because of hype.
I hope this very long read helped dress you for a fun prerelease and a limited format which is going to be serious business with Grand Prix London (which I will be attending) in the beginning of February and be relevant until M14 hits the shelves. Go out to your local prerelease(s) and put this advice into action, (most importantly) have fun exploring the cards for yourself, and if you care, come back with feedback from your own experiences with the cards. I will be getting into drafting once we have Gatecrash out for real. Until then!
@Lobster667 on Twitter.