Dragon Turtle Shell

When you are struck by an opponent’s natural attacks, the damage is resolved as if the attack came from a creature one size smaller per 5 caster levels (maximum of four size categories smaller at CL 20th). Refer to Table 3–1 to determine an attack’s altered base damage. If the creature’s natural attack deals nonstandard damage, refer instead to the Improved Natural Attack feat. It is not possible to reduce the base damage of a creature’s natural attack below 1d2 with this spell.