Thorn Hide

You touch a willing creature. Until the spell ends, the target's skin covers itself in a thick cording of thorny vines and the target's AC can't be less than 15 + their Dexterity Modifier (Maximum of +2) regardless of what kind of armor it is wearing. In addition, whenever a creature within 5 feet of you hits you with a melee attack, the thorny hide lashes out at the attacker. The attacker takes 2d4 magical piercing damage.