Heimerdinger Presents:
Dark sorcerer, master of forbidden magic, aspiring lich—all could describe Karthus Lightsbane, a high level spellcaster with shadowy motivations. The rest of the party is convinced he'll eventually betray them, since nothing in the Riftquest rules says he can't.
Sadly there are no chromas for Karthus Lightsbane Karthus yet.