Blood Transfusion

You siphon your own blood to restore vitality to another. As you extend your will, crimson threads of blood spiral from your wounds and flow into a creature you can see within range. You take 4d8 necrotic damage which cannot be reduced in any way. The target regains hit points equal to twice the necrotic damage you suffer.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.