Throrgrim's Reanimate

With this arcane ritual you attempt to force a creature's soul to re-animate its corpse, creating an undead creature whose soul is trapped in its own rotting corpse and unable to transition to its next phase of existence.

The ritual portion of this spell must be performed for a number of days equal to the class level or challenge rating of a specified target creature. Set your incense burning and make a circle of mercury, incant the words of the spell incorporating the target's name or specific description and meditate within the circle for at least 8 hours each day; you must ensure that incense is continuously burning for the entire duration of the ritual. (You may employ assistants to manage the incense burning.) The ritual is complete when the circle of mercury evaporates; you may then cast the spell, if you have an available 8th- or 9th-level spell slot, by touching the target creature's freshly killed corpse. If the target creature has been dead for more than 8 hours or if the target is already undead or a construct, the spell fails automatically. The target creature's soul, using its normal statistics from life, must make a WIS saving throw against your Spell DC. On a successful saving throw, the spell has no effect; on a failure, the soul instantly re-animates its corpse, becoming an undead creature.

The re-animated creature has the same abilities and hit points it had in life, but its personality and alignment will be affected by its transition to un-death: it will be prone to madness; it will hate the living; it will have difficulty remembering its past, and it may be self-destructive. If the undead creature endures for 1 year, it has a 50% chance of embracing its undead nature and the same chance to become despondent and seek its own destruction. For each additional year it endures, its chance of fully embracing un-death increases by 5%.

The undead creature's attitude toward you will depend upon its intelligence; the higher its intelligence, the more likely it is to be hostile toward you. The spell gives you no control or influence over the creature.

As an undead creature, the target has no need for the requirements of life. It gains Darkvision to 60'; it is Immune to poison, and cannot become poisoned or suffer from exhaustion. At the DM's discretion, creatures may gain other benefits and vulnerabilities as a result of being successfully targeted by this spell.

If the target creature is reduced to 0 hit points, its soul is freed from your spell.