Book of Vile Darkness 3.5
By Monte Cook
The caster detaches his hand, which transforms into a Small monstrous spider that he controls. The caster can see through its eyes, and it can travel up to 20 feet per level away from him. If the spider is killed or prevented from returning to the caster, his hand is restored when the spell ends, but he takes 1d6 points of damage. If the caster directs the spider to return to his arm (a move equivalent action), then lets the spell end, he takes no damage.