Azar's Suspended Soul

You touch the body of a recently dead creature, the soul of the creature is thrown into a demiplane which appears however the soul chooses. While captured in this way, the body keeps some connection to the soul and spell components (if a value is needed) for a resurection spell cast at the target of this spell cost half as much, the timeframe to cast the spell is also doubled, (i.e. revivify would be able to revive a corpse that had been dead for no more than 2 minutes).

If the body is resurrected using a necromancy spell that would turn the target into an undead, it instead turns the target into a lesser form of revenant. The target gains the undead tag as well as the rejuvenation ability. The targets speed is also cut in half.