Spirit of vengeance
From WoWWiki
Spirits of vengeance are creatures that form when an avatar of vengeance slays a humanoid. Avatars of vengeance can also summon spirits of vengeance from corpses. In some ways, spirits of vengeance are like lesser versions of avatars of vengeance — they are composed utterly of revenge. Unlike avatars, a spirit of vengeance contains bits of humanoid soul mingled with the vengeance energy. The avatar of vengeance that created the spirit has full control over it. Spirits of vengeance do not speak, but they do utter animalistic growls.
Spirits of vengeance possess little of the cunning of the avatar that created them. When uncontrolled, they move toward living creatures and hack them apart. Some spirits target specific creatures particularly deserving of vengeful judgment, ignoring innocents. A spirit of vengeance’s weapon is a shadowy extension of itself. Their weapons can take many forms; most resemble either the weapon of the avatar that created them or the weapons of the living creatures from which they were summoned.APG 213
Greater Spirit of Vengeance
A greater spirit of vengeance is the embodiment of revenge. The creature has a vaguely humanoid form composed mostly of black wispy smoke. Its eyes glow bright red. In one hand, it carries a spectral whip that glows red with the same energy that burns in its eyes. When a powerful creature takes to the grave with intense feelings of hatred and business unfinished, she will occasionally rise again as a greater spirit of vengeance. A greater spirit of vengeance seeks to slay all living creatures in an effort somehow to bring peace to itself. It bears no feelings of guilt or remorse or pity. It takes its task seriously, treating all beings with equal disregard and sparing none that get in its way. A greater spirit of vengeance attacks with a long barbed incorporeal whip that drains the life from its victims. It makes full use of its incorporeal nature, moving through walls, ceilings, and floors as it attacks. It takes every opportunity to use its create spawn ability.MoM 93
