Onimus

Onimus is a necrotic magickal quintessence found within the bodies of undead creatures.
An alchemical method of extracting and refining Onimus from the undead has recently been discovered

Manifestation

While powering an undead creature, Onimus Magicks are undetectable by the naked eye.  While being drawn on by necromancers or warlocks, Onimus typically appears as a black, shadowy mystical energy.  On occasion it may appear purple-ish, or rarely as a sickly green manifestation.

Type

Metaphysical, Supernatural