Job

FP!

Like this.

All kidding aside, I say you should make him a cross between a goat demon and his usual look. With a tail and/or wings. The wings would be cool if you could dehack him to fly, but I'm not familiar with FreeDoom's rules on things such as that.

Well, the concept I envisioned for the Freedoom arch-vile is a tall skinny undead guy with pale, rotten, scabby skin, stitched/bolted/nailed together like Frankenstein's monster, with a rusted metal mask over his nose and mouth in the sort of design like a surgeon or dentist wears, other rusty metal plates and such grafted onto his limbs and torso, and evil glowing red eyes. When he attacks he clutches his forhead with one hand like he has a bad headache while pointing at his target with the other hand, and when he resurrects something he kneels next to its corpse and holds one hand over it.

If I didn't totally suck ass at drawing sprites, I would've tried to make it myself, but my skill is not enough.