Soulswitch

Necromancy
Level: Bard * 5, Cleric */Oracle * 5, Druid * 5, Hunter * 5, Inquisitor * 5, Magus * 5, Shaman * 5, Sorcerer */Wizard * 5, Warlock * 5
Components: V, S, F (two brass collars worth 50 gp each)
Casting Time: 1 Standard Action
Range: touch
Target: you and your familiar
Duration: 10 minutes/level
Saving Throw: Will negates (harmless)
Spell Resistance: yes (harmless)
  You may only cast this spell if you currently have a familiar. You place your soul into the body of your familiar, and your familiar's soul is placed in your body. This functions as if you possessed your familiar using magic jar; your familiar simultaneously possesses your body in the same manner. You can't freely transfer your soul between your body and your familiar's-if you choose to return to your body as a Standard Action, the spell ends. If either body is killed, both spirits return to their original bodies, the spell ends, and the original owner of the slain body dies.