Those of you who are fanatics of the WoW TCG have probably heard of the new Servants of the Betrayer expansion already, but even if you have, it's worth checking out this new article on the official Upper Deck TCG site. It goes into greater length about the philosophy behind the new cards, and introduces the basic ideas, mechanics, and lore behind the new Traitor Heroes. While "Servants of the Betrayer" rightly assumes you'll be able to control Vashj and Kael, they decided that they did not want to make those two central to deck building, since they already plan to release a new Black Temple raid deck later on. Instead, they will be possible allies of a new series of "Traitor Heroes."
The new Traitor Heroes will, apparently, be twins of existing heroes, only "evil mirror universe" versions, having at some point rejected the teachings of the Alliance and Horde to join a traitorous faction with the WoW Universe, such as the Scarlet Crusade, the Grimtotems, or the Leper Gnomes, among others. These heroes will have access to a pool of Traitor allies which will include Kael and Vashj, as well as access to various traitor abilities that, like the traitor heroes, will be brutal mirrors of existing abilities (for example, the traitor version of Execute, which destroys a target damaged ally, is called Sudden Death, and will instead destroy a targeted undamaged ally). Finally, each Traitor Hero, in addition to having the traitor allies, will also be able to use ally cards from their betrayed faction. for example, the Grimtotem traitor will be able to coerce the Horde into working for him, and the Leper Gnome traitor will be able to infect Alliance allies to go crazy right along with her. That way, if they can't work new traitor allies into subsequent expansions, traitor heroes will still be able to grab some help.
OK, so next thing you're asking is pretty obvious: Where's the downside? Should I be throwing out all my old cards and working on a traitor deck? There is a catch, yes: Traitor heroes cannot use talents. So you'll have a new pool of abilities and allies to work with, but you'll have to give up Mortal Strike.
I have to say, I'm intrigued. We're talking some awesome lore possibilities for the lore geek and raving Grimtotem fanboy in me, and it should be interesting to see how many players decide that it's worth it to give up talents for the new traitor ability and ally cards. The information's only going to keep coming, as Upper Deck will release 2 new preview articles a day covering various new abilities. It should be a great ride for fans of the TCG.