The concept is very good.
I saw two bugs:
1) Wight's curse doesn't work as advertised: it doesn't resurrect the deceased hero as a zombie, but as a clone of (I suppose) the monster that killed him. So if a hero afflicted by a wight's curse dies at the hand of a pit fiend, it creates a pit fiend, not a zombie. (this can lead to funny outcomes where a single surviving hero must fight four epic or legendary monsters in the same room)
2) The lich's power doesn't seem to work as advertised either. For instance, I put a lich on the room next to a treasure room, but my fleshbags on the other side of the floor or even in the previous room never resurrected as skeletons or anything else.
