Exaction

Exaction was a divine evocation and alteration spell that summoned a planar being to strike a bargain for a service.

Effects
Possible creatures that could be summoned from another plane of existence included devas, devils, and demons, but nothing as powerful as a demigod. The caster needed knowledge of the creature to use as leverage for striking a bargain, or else he or she had to offer something in fair trade, possibly a gift, monetary compensation, forgiving a debt, a favor, or a service in return. Creatures of opposing alignment (good vs. evil, lawful vs. chaotic, or true neutral vs. any of those) to the caster could not be summoned unless it was willing. Once a reasonable balance had been achieved between the task requested, the previous debt or promised favor, the relative risk to the creature, and the value of the compensation, etc., then the spell took the form of a quest on the summoned creature. The creature got one chance to resist the spell, but it was typically automatically binding if the creature was willing or found the terms favorable. Once the task was completed, the creature was instantly transported to the caster's vicinity to conclude the bargain and the caster was required to immediately provide the promised reward. When this was accomplished, the creature was freed from service at once.

During the negotiations, if the caster offered too little or asked for too much, the creature was free to leave or attack as it saw fit. Similarly, if the caster failed to hold up his or her side of the bargain, the creature received complete immunity to the divinely granted spells and powers of the caster and could attack without fear. A more salubrious outcome was that the caster became subject to exaction by the cheated creature. If the creature died while performing the task, and the element of such a risk was not factored into the agreement, then the caster could be subject to exaction by the relatives or the master of the deceased.

Components
In addition to verbal and somatic components, this spell required use of the priests holy symbol, a bit of matter from the same plane as the creature being summoned, and a piece of parchment upon which is written the information pertaining to the reason for the exaction and/or the actions required. This parchment is burned to seal the bargain.