Ermor (Ashen Empire)is an Undead nation pretty much the way it was originally in WFB3, before the split between Vampire Counts & Khemry.

The game is easily modable.

Back in Dom2 there were mods for 2 orc empires, forest elves & dwarves...not sure if those have been converted to Dom3, but it should not be too difficult.

With some patience you might be able to create a mod yourself that mirrors any nation from Warhammer.