Your body changes, granting you a powerful unarmed attack.
The Netbook of Witches and Warlocks
By Timothy S. Brannan and The Netbook of Witches and Warlocks Team
With this, you can make unarmed attacks without provoking attacks of opportunity, are always considered proficient with the attack, and also deal 1d4+1 point of damage (max +15) per level.
The type of damage (piercing, slashing, or bludgeoning) granted changes between each caster. Usually, if you have a familiar, the spell will mimic the attacks that a familiar might have. For instance, a caster with a ram familiar may grow horns. One with a cat familiar will have small, retractable claws. A bird familiar may cause the caster to grow a beak to peck with, or a toad familiar may grant a slapping tongue. If you do not have a familiar, you simply grow long animal-like claws.