Acid Sheath

You enclose yourself in a thin vaporous film of acid that doesn't harm you. Any creature within 5ft of you that hits you with a melee attack takes 1d4 Acid damage. A creature also takes this damage at the start of its turn if you are grappled by it.

Additionally, you gain a +1 bonus to each dice roll of Acid damage that you deal.

At Higher Levels. When you cast this spell using a 2nd level slot or higher, the damage in response to attacks and grapples increases by 1d4 per slot level above 1st. Additionally, the duration increases by 1 round for each slot level above the first.