But to answer the question, none of the Stygian powers can create undead. Most are just negative levels.
Question: What do you get if a creature is killed via negative levels?
und making more wights, that are under its command. et alli.
But there are no equivalents to Animate Dead for you to make Awakened Remorhaz Skeletons. No Create or Greater Create to make Bone Creatures, Shadows or any of the other Dread Necromancer fun-bags for Psions. UNLESS you're using spell-to-power.
There is Psianimate Dead, from Hyperconscious, which can make some incredible critters if you really try, though it's not a specific kind of undead creature.
Do keep in mind that the undead you create keeps its memories and mental ability scores, meaning that it should have the same personality as before it died (though subject to slavery by you, should you wish to enforce it).
This can be quite useful, I think, even if your vict...err...friends lose class levels because of it.