By Honorah O'Neill (firstname.lastname@example.org) for the Breakers tribe.
System: The Ritemaster takes a vessel full of pure water and summons a spirit of Pain and a spirit of Truth. These are then bound into the water, roll Manipulation+Rituals difficulty 8. The ones making the deal must take a sip of the water and then recite the exact terms of the deal and then take another sip. If they should try and break their word they will be wracked by crippling pains for a week after they break it, or until they make the effort to actually do as promised.