School: Chronomancy (Transmutation)
(Intended for use with the Chronomancer subclass)

This spell permanently detaches the caster from his lifeline. This negates the rule concerning doubling lifelines, and that's all most casters should know.

The material components are a small silver knife enchanted to store a Lifeline Tether, and diamond dust worth 10,000 gp, sprinkled across the blade. This spell is cast while the caster is on the demiplane of time, and the knife is used to physically sever the caster's lifeline at the point it turns into the insubstantial silver mist trail.

DMs should know: severing one's lifeline essentially ends a character's life... at least in the traditional sense.  In some ways, this is analogous for the Chronomancer as lichdom is for a wizard, though they are not undead, nor does their alignment change as a result of the procedure.  Their mortal lifeline no longer extends into the future.  They are no longer considered "natives" of the Prime Material, and are instead now considered natives of the demiplane of time.  If they are destroyed, their essence returns to the demiplane of time, and their soul is lost.  They can no longer go to any heaven or hell, nor become petitioners to any of the gods or Outer Planes, as they are already essentially "petitioners" of Time. This is true unless direct intervention from one of the Major Powers (or a DM-decided method of altering this state of existence) occurs.  They are no longer temporally linear beings, and can be banished from the Prime Material as though Outsiders.  They can no longer be affected by paradoxes, and no longer cause paradoxes by visiting their own past history.  They are now susceptible to any spell or effect that damages or disrupts a native creature of the demiplane of time.  Their fate and ultimate well-being is now directly linked to the fate and well-being of the temiplane of time and the Timestreams.  Guardians of the demiplane of time will almost certainly attempt to contact any Chronomancer who severs their own lifeline as soon as possible, for better or worse.

Inspired by the 2e AD&D spell Sever Lifeline, from the Chronomancer suppliment (TSR 9506).