Pseudo-lich

A pseudo-lich was a form of undead that was superficially very similar to a lich. It was created when a powerful wizard's soul refused to leave their body upon death.

Description
Pseudo-liches resembled real liches in most respects, although they had not undergone the dark ritual that characterized a lich and therefore did not have a phylactery. Instead, they were animated by an unknown force&mdash;perhaps their own will or their intense exposure to magic&mdash;that fed off of a goal or obsession they held at the time of their death. A pseudo-lich would crumble to dust upon achieving its goal, or alternatively, its animating force was quite unpredictable and could fail at any time. They could not manage to exist for more than a century at most.

Personality
A pseudo-lich was fanatically engrossed with whatever goal or research it was pursuing at the time of its death. It was wholly unconcerned with anyone or anything that did not relate to&mdash;or impede&mdash;its work.

Combat
A pseudo-lich was a powerful arcane spellcaster and wielded many of the same powers as a true lich, however they lacked both the invincibility that came from having a phylactery as well as the deathly cold and paralyzing touch for which liches were feared. However, like liches they projected an aura of fear and could not be turned, charmed, put to sleep, enfeebled, or polymorphed, nor could they be affected by electricity, extreme cold, or any magics that sought to inflict insanity or instant death.

Society
Pseudo-liches were unable or unwilling to pursue true lichdom.

Unlike true liches, they were capable of procreation.