A wu jen cast this spell when they needed to obtain the service of a greater or lesser spirit. Before casting the spell, the caster was required to cast a commune with greater spirit or commune with lesser spirit spell to establish communication with the target spirit.
The spell was unable to compel a spirit into service. The caster could compel the spirit by offering a coveted item or provide a service demanded by the spirit. Once a deal was made, the spirit was then compelled to complete the service.
After a successful bargain, the wu jen chose whether to make their payment immediately or wait until the service was completed. If the wu jen failed to complete their side of the bargain, the spirit could appeal to the Celestial Bureaucracy, at which point the wu jen could be punished until their side of the bargain was completed.