Thorn Skin

You stretch your body as you raise your arms above your head, causing thorns to sprout all throughout your skin. For the duration, whenever a creature hits you with a melee attack, thorns shoot out from your skin, dealing 2d8 piercing damage to the attacker. A creature that has you grappled, takes 4d8 damage at the start of each of its turns, and must succeed a Constitution saving throw or be forced to release you