Priest's Spell Compendium[]
When this spell is employed, the priest confronts some powerful creature from another plane (including devas and other powerful minions, for instance, but not demigods or deities of any sort) and requires of it some duty or quest. A creature of an alignment opposed to the priest (e.g., evil if the priest is good, chaotic if the priest is lawful) cannot be ordered around unless it is willing. Note that an absolute (true) neutral creature is effectively opposed to both good and evil, and both law and chaos.
The spellcaster must know something about the creature to exact service from it, or else he must offer some fair trade in return for the service. That is, if the priest is aware that the creature has received some favor from someone of the priest's alignment, then the exaction spell can name this as cause. If no balancing reason for service is known, then some valuable gift or service must be pledged in return for the exaction. The service exacted must be reasonable with respect to the past or promised favor or reward, and with the being's effort and risk. The spell then acts, subject to a magic resistance roll, as a quest upon the being that is to perform the required service. Immediately upon completion of the service, the being is transported to the vicinity of the priest, and the priest must then and there return the promised reward, whether it is irrevocable cancellation of a past debt or the giving of some service or other material reward. After this is done, the creature is instantly freed to return to its own plane.
The DM adjudicates when an equitable arrangement has been reached. If the caster requests too much, the creature is free to depart or to attack the priest (as if the agreement were breached) according to its nature. If circumstances leave the situation unbalanced (for example, the creature dies while achieving a result that was not worth dying for), then this might create a debt owed by the caster to the creature's surviving kith and kin, making the caster vulnerable to a future exaction spell from that quarter. Agreeing to a future exaction or release in the event of catastrophic failure or death are common caster pledges in securing an exaction.
Failure to fulfill the promise to the letter results in the priest being subject to exaction by the subject creature or by its master, liege, etc., at the very least. At worst, the creature can attack the reneging priest without fear of any of his spells affecting it, for the priest's failure to live up to the bargain gives the creature immunity from the priest's spell powers.
The material components of this spell are the priest's holy symbol, some matter or substance from the plane of the creature from whom an exaction is expected, and knowledge of the creature's nature or actions that is written out on a parchment that is burned to seal the pledge.
Notes: Common for clerics (PHB).
Encyclopedia Magica[]
Definition: A priest using this spell confronts a creature from another plane and requires of it some duty or quest.
The spell will not affect creatures with alignments greatly opposed to the priest's (such as good vs. evil or law vs. chaos). Note that a true (absolute) neutral priest is greatly opposed to all other alignments, for the purposes of this spell. A creature which can be affected receives no saving throw, nor will magic resistance protect it. However, this spell does not affect deities or divine beings.
If the creature has received a great favor in the past from a person of the priest's alignment, the priest can name this as a reason for service. This requires that the priest know the personal history of the creature. If no past service is known to the priest, he or she must pledge a valuable gift or favor to the creature in return for its service. In all cases, the reward promised by the priest must be equivalent to the service required from the creature. The spell then forces the creature to perform the service agreed upon. If the creature fails to perform the mission, it will suffer the penalties of the spells geas and quest simultaneously, until the mission is completed. Creatures cannot be compelled to obey self-destructive or suicidal commands.
When the service demanded from the creature is performed, it is instantly teleported to the priest's location. The priest must then perform the service or grant the reward agreed upon. When the creature's reward is granted, it is immediately sent back to its own plane.
If the priest reneges on the agreement, the creature has two options to choose from. Each is a part of the original spell and does not require magical ability or spellcasting from the creature. Should the agreement be broken, the creature can place the priest under exaction. The priest receives no saving throw against this effect. Otherwise, the creature can attack the priest. Should it choose to do this, it will be totally unaffected by any spells cast by the priest.
The material components of this spell are: the priest's holy (or unholy) symbol, matter from the home plane of the creature from whom an exaction is required, and knowledge of the creature's nature or past actions written on a page of parchment which is burned to seal the bargain.