Transfusion

This spell heals one's undead minions in exchange for some of their own life and blood. When you cast this spell you sacrifice 2d4 hit points to heal each of your minions under your control from necromancy spells by 1d4 hit points.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, your minions heal by 1d4 more HP for each slot level above 3rd.