There are two types of Necromancers so far, apprentices and masters. Apprentices can summon [[zombie]]s from corpses(Only humans, no animal zombies yet.in the current versions) and masters can summon zombies and skeletons, including a one-time summon of [[Xinroch]]. Necomancers in groups are a problem if there is more than one, since they will teleport, summon the dead, and launch spells like the ones that dark mages launch. If you encounter a lot of undead and/or the ones that you kill come back to life, it's a tip that there is a necromancer on the level.