[Taqwus]

Hmm. Might be right on CoD; I'm not very heavy on death casters in my current game so I haven't seen it used for a while.

On a related note, undead will also ignore the disease effects from certain death magic (leprosy bombardment, say), generally can ignore decay (since they tend to have high maximum ages) and tend to be pretty resistant to fear effects (most being either mindless and completely immune, or good morale/good MR... ghouls might be an exception), and also perform perfectly fine under Darkness and Rigor Mortis. Poison is also an obvious complement, since undead tend to be completely immune.