Death knell was a necromancy spell that finished off a dying subject and sapped his energy to strengthen the caster.
The caster drew forth the ebbing life force of a badly wounded creature and used it to fuel his own power. Upon casting this spell, the caster touched a living creature that was near death. The caster had a chance of killing the creature and if it died the caster became temporarily stronger and more powerful. The duration of the spell lasted from a few minutes to several hours depending on the power of the target.