Veth's Very Venal Vendetta

Whenever you are hit by a spell attack, melee attack, or ranged attack, you can cast this spell. As a reaction, you can cast this spell and the creature that attacked you must make a Wisdom Saving Throw. On a success they take half damage. On a failure, they take 3d8 psychic damage and have disadvantage on their next 2 attacks against the caster.  

At higher levels, the damage for this spell increases by 1d8 per additional spell level above 2nd.