You cause your body to produce a caustic acid. You and anything you were holding or carrying when the spell is cast is immune to the acid. While the spell is active, you can make a melee attack roll against a target, dealing 4d4 acid damage on a hit. If you are grappling a creature, it takes the acid damage every round on your turn, as if you had made a successful attack. If you are grappled by a creature, or restrained or immobilized by physical means (ropes, chains, or similar restraints), the creature or the restraints takes the acid damage each round.