Backbiter(Spell Compendium, p. 23)
Level: Sorcerer 1, Wizard 1,
Components: V, S, AF,
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One weapon
Duration: 1 round/level or until discharged
Saving Throw: Will negates; see text
Spell Resistance: Yes (object)
The weapon you indicate during the spell's casting briefly shimmers with a black aura that disappears in an eyeblink.
You cast this spell on any melee weapon. The next time that weapon is used to make a melee attack, its shaft twists around so that the weapon strikes the wielder instead. The weapon hits automatically, and no attack roll is made.
The wielder gets no warning or knowledge of the spell's effect on his weapon, and although he makes the attack, the self-dealt damage can't be consciously reduced (though damage reduction applies) or changed to nonlethal damage. Once the weapon attacks its wielder (whether successfully or not), the spell is discharged.
Magic weapons targeted by this spell receive a Will save. An item in a creature's possession uses its own Will save bonus or its wielder's bonus, whichever is higher.
Focus: A dagger.