Blood Transfusion

You prick your finger and point it at a target you can see within range. The target regains hit points equal to 10 + your spellcasting ability modifier. At the end of each of it's turns for the duration of the spell, the target must make a constitution saving throw. On a failed save it takes 1d10 necrotic damage, on a successful save, the spell ends.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the blood cost and hit points regained both increase by 1 and the damage dealt increases by 1d10 for each slot level above 1st