death knell

You draw forth the ebbing life force of a creature and use it to fuel your own power. Upon casting this spell, you touch a living creature that has 0 hit points. If the target fails its death saving throw it dies, and you gain  1d8 temporary hit points and a +2 bonus to Strength. Additionally, your effective caster level goes up by +1, improving spell effects dependent on caster level. (This increase in effective caster level does not grant you access to more spells.) These effects last for 10 minutes per HD of the subject creature.