Synopsis: Main character Lysa is the protagonist and has powers. The main antagonists are necromancers, and the head bad-guy, Drakken, is a major nasty dude. (I won't give more specific than that at this point unless the reading group wants spoilers!) I'm still pinning down the necromancer specifics, but basically they kill people to make themselves stronger magically.
The writing group wants more specifics about the things Drakken has done so that when he arrives on the scene, that the readers will be properly freaked out and scared for Lysa's well being.
I know what he's done (don't want to give spoilers) to a small extent, so I need to write some proper terrible stuff he's done. Only, it's freaking me out to write it. My simple Mormon girl sensibilities are in danger of corruption. But I still want help.
As for creepy vs nasty. I need him to be more nasty. The writing group said 'creepy', but that's not really the feel I'm going for. I don't want it to feel like Sauron, all-powerful and completely corrupt. Drakken has motives that make sense to him, and he's more rounded out than that (ok, can't say more, spoilers...).