It's better to let professionals draw the first blood...

Every year, all tribes gather for the Great Thing. Supervised by feared judges and in the face of ruthless deities, each and every person who feels harmed or wronged may prove their rights on the bloodied sands of the Arena of the Righteous. Such persons may challenge the alleged wrongdoer to single combat and seek retribution for any crime - or at least that's what the Ancient Law states.