[HoneyBadger]

I'm thinking it has something to do with Dominion. The most obvious answer is that it's related to insanity, but we hardly need a whole new ability to reflect that-and I don't see a reason for them to turn into Eaters of the Dead-and insanity already can make a unit basically uncontrolled. I think it *might* be that they'll decide to try to become Pretenders, themselves, because their souls are too fractured for Pretenders to fully control them. So you may suddenly find Tartarians turning against you and hurting your Dominion. Also, it may be a specialized "anti-magic" ability that protects them from certain spells that would normally affect a being's soul in the game. It's possible that the pieces of their "shattered soul" may find their way into opponents, turning them to your cause or making them insane. Or maybe it works like a disease, only a "disease of the soul" that gradually warps and mutates the Tartarian's essence, adding or subtracting abilities and defects.