Undead Level Advancement

Old Geezer posted a story on RPGNet about a vampire PC and his flying undead army encounter another band of vampires and spectres in the sky. The GM of this particular group had newly-minted vampire victims rise as skeletons and "progress" through the standard undead types. And, therefore, when one undead drained an undead opponent, the opponent "regressed" to a previous undead type. (See his post for the humorous consequences.)

Now, some people in that thread objected that this broke their expectations of the way a fantasy world should work. A zombie with rotting flesh shouldn't become incorporeal as it gains level, then become corporeal with intact flesh when it finally becomes a vampire! Honestly, if you're going to use an amusing rule like this, you shouldn't be griping about "realism". But, for their sake, here's an idea: separate "tracks" for corporeal and non-corporeal undead (and a possible third track for mummies.) Actually, skeletons are half a HD, in Monsters & Treasure, not 1 HD as in OG's example. So let's make a skeletal undead track as well!

Undead Progression Tracks

HD		Corporeal		Skeletal		Non-Corporeal
1		Zombie		Skeleton	*	Phantasm
2		Ghoul	?	Coffer Corpse	*	Shade
3		Wight	*	Bone Wight	*	Phantom
4	*	Tomb Dweller	*	Tomb Remnant		Wraith
5-6	*	Unhallowed	*	Tomb Lord		Spectre
7-9		Vampire	*	Walking Relic		Spectral Lord
10+		Vampire Lord		Lich	?	Ghost

Undead marked with an asterisk are those I plan on writing up. Those marked with a question mark I might modify, but have official write-ups (for AD&D, but they'll work for OD&D as well.) The vampire lord and spectral lord would be just standard vampires and spectres, but with more hit dice and a couple extra powers:

Vampire Lord

Roll once for random reversed 5th level Cleric spell as a daily power

... But replace Commune with Feeblemind and Create Food with Animate Dead

Spectral Lord

Roll once on angry spirit variants table for an addition power