So I'm DMing, and one of the characters has in their backstory that they killed a king by accident (and are thus on the run). I want to bring that king back as a big villain, but I need advice on how I'd actually do that.
My main concern his keeping his memory. I could have him come back as a classic zombie, but I'd think that would make him a mindless pawn like all other zombies. I'd need some way to cheat death, bring him back, and possibly give him superpowers (like sorcery or whatnot).
My best idea right now is for him to have become an infernal sorceror, making a deal with a big-shot devil to come back from the dead to serve him. But is there a better way?