Blood Sacrifice

You can draw upon the life force of a creature to replenish your own health. This creature must make a con save (unless its willing). The creature must have blood. On a failed save, the creature takes 2d10 necrotic damage as its blood is turned into green energy and sapped by the caster.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d10 for each slot level above 1st.