There's little in the way of permanent minions (and mostly needing a reskin from other classes for that, as mentioned). There's a range of summoning powers that bring out undead, but summoning is on a pretty strict action economy, so not a complete strategy in and of itself. There are necromancy- and undead-themed conjurations and zones (skeletal hands shooting out of the ground grasping at people, stuff like that) and various debilitating offensive spells and life force manipulating ones (getting temp HP when things die, stuff like that). Animating fallen enemies is implemented as summoning powers that target dead creatures.