If a consensual contract is agreed upon, without coercion or Master effects involved, though bribery is fine, all parties must follow through. All parties must be aware of the power. This power works on you even if you're immune to Master powers, and won't work if another power is immune to it. You must be one of the involved parties, even if the contract just labels you as a witness or arbitrator. Be careful to look for loopholes. This power fails if the contract becomes impossible to fulfill.