Casting this spell attempts a dangerous act: to lure a creature from another plane to a specifically prepared trap, which must lie within the spell’s range. The called creature is held in the trap until it agrees to perform one service in return for its freedom.

To create the trap, the character must use a magic circle spell, focused inward. The type of creature to be bound must be known and stated. If it has a specific, proper, or given name, this must be used in casting the spell.

The target creature must attempt a Will saving throw. If the saving throw succeeds, the creature resists the spell. If the saving throw fails, the creature is immediately drawn to the trap (spell resistance does not keep the creature from being called). The creature can escape from the trap with a successful SR roll, dimensional travel, or a successful Charisma check (DC 15 + 1/2 its level + its Charisma modifier). It can try each method once per day. If it breaks loose, it can flee or attack the character. A dimensional anchor cast on the creature prevents its escape via dimensional travel. The character can also employ a calling diagram to make the trap more secure.

If the creature does not break free of the trap, the character can keep it bound for as long as the character dares. The character can attempt to compel the creature to perform a service by describing the service and perhaps offering some sort of reward. The character makes a Charisma check opposed by the creature’s Charisma check. The DM then assigns a bonus based on the service and reward, from 0 to +6. This bonus applies to the character's Charisma check. If the creature wins the opposed check, it refuses service. New offers, bribes, and the like can be made or the old ones reoffered every 24 hours. This can be repeated until the creature promises to serve, until it breaks free, or until the character decides to get rid of it by means of some other spell. Impossible demands or unreasonable commands are never agreed to. If the character rolls a 1 on the Charisma check, the creature breaks free of the binding and can escape or attack the character.

Once the requested service is completed, the creature need only so inform the character to be instantly sent back whence it came. The creature might later seek revenge. If the character assigns some open-ended task that the creature cannot complete though its own actions (such as "Wait here" or "Defend this area against attack"), the spell remains in effect for a maximum of 1 day per caster level, and the creature gains an immediate chance to break free. Note that a clever recipient can subvert some instructions.

When the character uses a calling spell to call an air, chaotic, earth, evil, fire, good, lawful, or water creature, it is a spell of that type. For example, lesser planar binding is a water spell when the character casts it to call a water elemental.