Instead of summon wraith. The last half of the necromancer passive tree is full of bonuses to skeletal mages and passives that mostly benefit skeletal mages better than other minions. In addition the mastery bonus for Necro is literally just +1 to skeletons and skeletal mages.
Maybe im just unaware of any other builds that would bother with skeletal mages that arent necro, but it seems to me like there’s already so much overlap here, and the necro passive tree has literally nothing that specifically benefits wraiths anyway. This has always seemed weird to me.
This is aside from the topic that the necro tree could probably benefit from a refresh.