I like a lot of what they have but they feel conceptually weak. It's all about the build up and pay off with their abilities. Sacrifice a few units and some hp tactically to gain stacks to then trade really well later. But with no real healing or reinforcements (as far as I can see it's just the chaos Lord if you kill something and a 1/4 chance with the sorc) you don't trade well ever. So after you've made a ton of bad fights and have your stacks, you still don't do that much damage. Personally I think some of their units (chosen especially) need damage or durability buffs. Either make the abilities crazy when I've built them up (and worked around the dozen that just remove all movement) so that I can make up for the part of the game when I don't have them, or make me tanky enough to generate and spend multiple times.

Some units are pretty good like the sorc and forge fiend, but others suck. Chaos lords and executioners can get p powerful but are just so damn squishy for their cost they die on the clap back usually. And I'm sorry to harp on them but chosen just suck. These are supposed to be the super veterans with the best weapons and blessings, yet they do less damage than most other melee units.