When this powerful spell is employed, the wizard transfers his spirit to the body of an undead creature, totally dominating it. If the undead creature has intelligence, it is allowed a saving throw vs. spell to resist the joining. If the save is successful, the caster's spirit is forced back into his own body. The wizard must make a system shock roll; if the roll fails, the wizard suffers 5d6 points of damage. If the roll succeeds, the wizard suffers half this damage.
If the creature's save fails, the necromancer joins his life essence with that of the undead. While in the creature's body, the caster can use all of its special attacks and innate abilities, excluding spells memorized by the creature.
The wizard's body remains comatose, is subject to all regular attacks, and suffers damage normally. The wizard's spirit can travel an unlimited distance from his physical body as long as they remain on the same plane of existence.
If intelligent, the possessed undead continually tries to purge the caster with mental threats that can be heard only by the wizard. The thoughts of the undead are ghastly. During the first minute of each hour of possession, the caster must succeed an Intelligence check in order to retain his sanity. The roll is modified by the difference between the creature's Intelligence and that of the spellcaster. If the undead has a higher score, the difference is added to the die roll. If the necromancer has a higher Intelligence, the difference is subtracted from the roll.
If the roll is successful, nothing happens and the caster may continue to possess the undead. If the Intelligence roll fails, the wizard's intellect degenerates, making him a raving, homicidal maniac. His spirit is immediately forced to return to his body, and he must attempt a system shock roll with damage occurring as outlined above. The caster remains dangerously insane until a heal or wish spell is used to restore his intellect.
This spell can be very useful when combined with the mask of death spell.
When the spell's duration expires, the necromancer's spirit immediately returns to his body.
Notes: Uncommon or rare (ToM).