You can use your expert understanding of Necromancy magic to put a greater undead thrall under your control. You may create a skeletal thrall to aid you in your day-to-day tasks, they can also be the target of spells and accompany you into combat but not as an actual combatant. You may use a ritual to raise a corpse of a fallen humanoid(Thralls) to act as the skeletal body.

3-day cooldown.