Acid Sheath(Spell Compendium, p. 7)
Conjuration (Creation) [Acid]
Level: Sorcerer 5, Wizard 5,
Components: V, S, M, AF,
Casting Time: 1 standard action
Duration: 1 round/level
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 2 points of acid damage per caster level (maximum 30 points). Reach weapons, such as longspears, 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 acid damage once per round at the beginning of their turn.
Any spell you cast with the acid descriptor while the sheath surrounds you deals an extra 1 point of damage per die.
Material Component: A handful of fire ants (alive or dead).
Focus: A glass sculpture of a humanoid (worth 50 gp).