Transfusion

You take 1d6 necrotic damage that can't be reduced. A creature you touch regains a number of hit points equal to twice the amount of hit points you lost this way. This spell has no effect on undead or constructs.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the necrotic damage increases by 1d6 for each slot level above 1st.