Greater planar binding

Greater planar binding was a conjuration spell that bound an elemental or outsider to the caster's service.

Effects
When cast, this spell shunted up to three weak elementals or outsiders into a trap from wherever it came from. The spell did not create the trap. It needed to be created before casting the conjuration spell. The trap was an inward magic circle-spell against the desired creature, for example a magic circle against evil if capturing a demon was the objective and a magic circle against good if capturing an angel was the objective and so on. The trap could be made more secure and by casting dimensional anchor on it, it prevented the trapped creature from teleporting away.

The creatures to be trapped had to be specifically named as part of the casting, but if one wanted merely a kind of creature, naming the kind was enough and a random specimen was called. Once trapped, the creature could try to break free by either overcoming the spell with its innate resistance against magic and/or its force of personality. If it had the ability to teleport, it could do so if the caster was careless enough to not having prepared for it. Each of these attempts could be tried once every day.

There was one sure way to get free for the trapped creature and that was to be released by the one who trapped it in the first place. This was usually done after a bargaining period between the trapped creature and the caster. The caster could try to force the creature into doing one specific task in exchange for freedom and could provide additional benefits to make the creature more inclined to accept the bargain. On coming to an agreement, the creature conducted the action, if an open-ended one for a period that depended on the caster's skill, reported the success of it to the caster and got free. If they did not come to an agreement, it was entirely possible that the creature eventually broke free and fought the caster.

Components
This spell required only verbal and somatic components.