You vanish and a monster of your choice appears in your place. The creature shares your alignment, personality and goals, and will continue to act as you would within the limits of its intelligence and abilities. The creature must be at least 3 CR less than your character level, may not have the incorporeal or swarm subtype, and is unexceptional for its type. If the monster is killed, the spell is ended. When the spell ends, the monster vanishes and you appear where the monster was with an amount of lethal, nonlethal, and ability damage on you equal to the amount the monster had suffered when the spell ended (this means that if the spell ended because the monster was slain and the monster had an equal or greater number of hit points as you, you may well be dead when you appear).