Well, that was my plan (update the nuke), but everyone seems a bit wary about it. So I considered replacements. :T
Tiefling 1/Ghost 2/Eternal Royal 17--The fact that Ghost means nuked HP is why I didn't start giving this stats. Immortal Smoke needs max HP, this can't get good HP... no matter how able you are to dodge something, if you can't improve your HP max, then it's a bad idea.
So then I thought Zodar 16/Balor 4: the Abyss's engine of destruction. Go for Drunken Demon... though that's bad because the strength overlaps with Ketaro and the size weirdness messes with Venn. Plus you can't get a Zodar drunk, ruling that out.
So I've been wondering Reth Dakala 4/Pseudonatural Creature 16. Take Forbidden School, pick Martial Study... get Immortal Smoke level 1 and Diplomacy as a class skill later on. "Cinder Knight of the Beyond" or something. Shouldn't overlap with others, has a stubborn tendency to survive, and things go nasty if they get in attacks. Not sure it's evil-fiendish enough, or if it doesn't compromise something from loss of nuking.