Thorn Body

This spell causes spines to grow from your exposed skin, damaging creatures that strike you. Any creature striking you with a melee weapon, an unarmed strike, or a natural weapon takes 1d6 points of piercing damage + 1 point per caster level (maximum +15). Creatures using melee weapons with reach are unaffected by this spell. In addition, your natural attacks and unarmed strikes deal an additional 1d6 points of piercing damage.