Acid Sheath

You enclose yourself in a fluid sheath of acid that does not harm you. You can breathe normally and cast spells while the acid sheath is present. Any creature striking you deals normal damage, but at the same time the attacker takes 2d4 acid damage. Reach weapons do not endanger their users in this way. The acid sheath does not protect you against other attack forms, such as fire. If you are in a grapple, other creatures in the grapple takes 2d4 acid damage once per round at the beginning of their turn. Any spell you cast that deals acid damage while the sheath surrounds you deals an extra 1 point of damage per die.