I've been playing a lot of Gatecrash draft since its launch online and spent most of my time getting frustrated that Pick 1, Pack 1s such as Homing Lightning and Truefire Paladin more often than not led me into a trap. With Boros widely regarded as the best guild and being one of the simplest to draft and play, I found myself surrounded by Boros drafters. Most wouldn't necessarily force it, but many commons, such as Skyknight Legionnaire, Mugging and Wojek Halberdiers were often enough by themselves to push into the Boros Legion. I found that Black was under-drafted and while Boros was very popular, most of the best Orzhov cards are either black, gold or don't fit the Boros plan.
The Five Key Commons
The best Orzhov deck isn't a control deck, it is an aggro deck in disguise. It can win races with any guild with lifegain/damage from extort combined with some of the most cost effective creatures (from White) and most of the best removal (from Black). It also had a good position in stalled board states from extort triggers and evasive creatures. Orzhov wants to prioritize cheap creatures, for an aggressive curve, and to gain the most benefit from extort triggers.
The following commons are the best for this game plan and I want my decks to be fleshed out with as many of these as possible. They are listed in no particular order.
A 2/2 for 2 will rarely steer you wrong in an aggressive deck, trading with almost all two drops and attacking well. The added extort provides a very strong mana sink and makes it relevant card even late game. It's not uncommon for the extort triggers to add up to a 6 or more lifepoint swing if left unanswered.
For similar reasons to Syndic of Tithes, this card does a lot of what you want. A 1/2 flyer for 2 wouldn't be overwhelming on its own, but extort is not to be underestimated. It deals damage in the air and like all extort cards, it adds up.
Wind Drake Would be well positioned in the format. With the added extort the card is liable to do a lot of damage.
In Orzhov, you want to be attacking most of the time, but if your opponent play a 4/4 of a 5/4 you'll need to leave guys back. You can then begin to just attack with flyers and extort them. They'll need to attack and when they do, you've kill their guy and get to activate all of your extort triggers. In a race this works as you can just attack, drop your next guy and leave up smite, though sometimes you need to not extort to keep the mana up and it can be obvious when you have it. This will usually work against flyers too because Orzhov has a lot of them.
Possibly the best common in the set, four mana, hard, instant speed removal. Kills almost every relevant creature except for Millennial Gargoyle and Armored Transport and they only become real threats when they're enchanted.
Devour Flesh, (Executioners Swing) and Angelic Edict and are all decent removal, Devour Flesh being the more situational. It is usually best used as a turn two play to keep other aggro decks off a critical mass, or in conjunction with other removal to kill two or more creatures. Angelic Edict is good, but a tad expensive. The fact that it exiles instead of kills is actually a slight downside, making Wight of Precinct Six and Death's Approach slightly worse. Also keep in mind that it can target enchantments, such as Debtor's Pulpit and Soul Ransom.
Balustrade Spy and Assault Griffin are both good evasive threats, but should almost never be picked over the top five commons. Keep in mind that Spy improves Wight and Death's Approach, so if you have Spies, pick them a bit higher and Vice Versa.
Gutter Skulk and Daring Skyjek are more important than they seem. They are cheap, which makes them great for extort, but more importantly they attack quite well or if you go on the defensive, trade very well. The Skyjek in particular is good for this.
High Pick Uncommons
The uncommons serve the same purpose as the commons but are harder to come by. Don't confuse rarity with strength, a lot of these should be picked lower than the premier commons, especially when considering curve.
One of the best removal cards in the set it is not uncommon for this card to do five or more damage during a dragged out game. It helps win board stalls and just helps win races in general. It's usually better than Grisly Spectacle due to this, but it loses value when combined with Devour Flesh, because they can just sacrifice the Lashed guy and like Angelic Edict it doesn't fuel Death's Approach.
Another fantastic removal spell, the downside being life loss. Much of this can be mitigated through sufficient extort creatures. This card will usually do what you want, one exception being killing their high-toughness creature while you are on a low life total. Though it does kill everything.
Removal that scales throughout the game. Kills everything if you have enough mana, if you have extort guys you can still get a lot of value from killing two or three drop later in the game.
A 1/1 with extort. The body is rarely relevant, but it can sometimes attack for a couple of damage is played turn 1, its cost makes it a decent top deck if you have a few extort guys out.
A good body with vigilance and extort. It can attack into a lot of board states, blocks well and like all extort, the ability does a lot of work. His casting cost is the main thing to consider when picking him as unless you have very few four drops, he will rarely be better than a Syndic of Tithes, if ever.
As a bear it already does a lot of what you want, letting you extort and attack for a good price. It has significant upside in that when you get to six mana you can give a creature lifelink and effectively double its damage.
Despite the intrinsic risks of an enchantment (getting two-for-oned) the upside of this card is incredibly high. It can turn most boards in your favor, either by letting you attack through anything, break a board stall or make an impassible blocker. Most guild don't have access to a lot of removal. The only real danger in red being Homing Lightning. Green and blue only really have access to Simic Charm, Hands of Binding and Totally lost. Though be wary when playing against other white or black players.
Same risks as Holy Mantle. This will lose value in a lot of Orzhov decks that are playing smaller creatures, or creatures that already have evasion. It would be a rare case indeed where I didn't run one if I got it, but be cautious in picking this over other important cards as it may not be well positioned in your deck.
Cartel Aristocrat is a bear with a strong upside. Normally just a 2/2 for two, which is still stronger than normal in Orzhov due to extort, but it can often deal the deciding points of damage in a board stall by sacrificing a creature a turn. It also holds enchantments well as you can kill your lesser creatures to protect it.
Wight of Precinct Six goes up in value the more removal and Balustrade Spies you have, but it is playable in almost any deck because it doesn't stay a 1/1 for long. Even without removal in a game where you've been trading it is a lot more relevant off the top than a random two drop.
Undercity Informer is pretty much always playable. Curve is very important in this format and as such he can be important to pick up if you're lacking three drops, though his value drops if you have a lot of two drop extort guys because you can just play a two drop and extort, lessening the importance of three drops.
Debtor's Pulpit is usually better than Angelic Edict in aggressive decks because you can effectively tap two of their creatures at once, letting you attack for a lot. Its cost can be a little prohibitive though, so it's rarely a very high pick unless your deck is very controlling.
Guardian of the Gateless is playable, but you want to avoid loading up on 5 drops. It shouldn't be picked too highly because it's replaceable with junk like Knight Watch and Nav Squad Commandos.
Cards to Avoid
In a format as fast as Gatecrash a low, fast curve is very important. As such it is important to avoid high CMC cards, Many players, including myself take this to the extent of picking six and seven drops very lowly. For example, avoid cards such as Luminate Primordial, (Sepulchral Primorial) and Treasury Thrull. While big, fun and cool, they are very costly and you will frequently see yourself overrun before you have enough mana to cast them. Unless your deck has gone down a very controlling path, which I would argue is something to avoid, particularly in this format, stay as far away from these as possible.
Unless taken late, or needed as filler, if your deck has not gone down the sub-par route of control, stay away from Corpse Blockade and (Bascilica Guards). As 1/4s they do little to advance your game plan of hitting your opponent. This is not to say unplayable. The Guards can get some value from extort and if against a deck with a lot of two drops might be good to bring in (most Boros decks for example). Unless you're low on playables or have a unique deck with mono evasion, you should try to avoid these.
A good Orzhov deck should have cheap threats, a low curve and removal. The bulk of this should be made up of as many of the top five commons as possible. The low curve maximizes aggression, keeps you alive and gets the most value from extort, so try to avoid five drops that don't have a very large impact of the game and consider avoiding six drops entirely. Good luck on the tables.