Bloody Rebuke

You point your finger, and the creature that damaged you is momentarily assaulted by spectral claws. The creature must make a Dexterity saving throw. It takes 2d10 slashing damage on a failed save, or half as much damage on a successful one. 

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.

Blood Magic (optional rule): When you cast this spell, you must take 1d4 damage unless you already have some of your blood on your person.