For cross-pollenation purposes let me give links to my mindless undead that are "use every part of the buffalo humanoid" based. How do people think they would synergize with this class? The empty-skin might be a bit cheesy since you could get a skeleton and a skin that both can use the breath weapon of the original or whatever.

Floating Lungs - (based around the Shout spell). Feel free to suggest a better name...

Hopping Stomach - Spits acid.

Gut Snake - Undead intestines that fight with constriction, filth, and odor.

Empty Skin - Macabre, but not always aggressive. Freak your characters/players out without a single die rolled... Intelligent servants for the necromancer just starting to come into his true power.

Dark Hearts - Literally pulsing with negative energy these repair the undead near them, and damage the living.

(Bladders with attached kidneys probably coming next. But also have plans for crawling livers, fat globs, rolling eyeballs, and slithering spinal cords.)