Heart Ripper

Heart Ripper
Necromancy [Death]
Level: Assassin 4
Components: V, S
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One living creature
Duration: Instantaneous
Saving Throw: Fortitude negates
Spell Resistance: Yes

Invisible bolts of force instantly slay the target you designate by driving its heart from its body unless it succeeds on a Fortitude save. If the target has HD higher than your caster level, it does not die on a failed saving throw, but instead is stunned for 1d4 rounds. Creatures that don't depend on their hearts for survival, creatures with no anatomy, and creatures immune to extra damage from critical hits are unaffected by the spell.