(extraplanar, inevitable, lawful)
Source: Bestiary 2, pg(s). 162
An arbiter is a clockwork sphere of bronze and copper measuring 1 foot in diameter and set with a single eye. It has two shiny metal wings and two clawed hands, one of which clutches a knife. Arbiters are surprisingly heavy, weighing 60 pounds.
An arbiter can always sense the direction of the nearest non-arbiter inevitable on the plane, the better to help it report back to its superiors. Despite their weight and the small size of their wings, arbiters can fly, which is as much a supernatural ability as a physical one. Their most powerful weapon, the ability to release their internal energy as a deadly burst, is reserved for dire need, as it will power down the arbiter for 24 hours.
Found throughout the multiverse in courts and on battlefields, arbiters keep a close eye on the forces of chaos and do their best to direct individuals to the lawful cause. Arbiters see themselves as advisers and counsellors, guiding their summoners on the path of law. They detest being summoned by chaotic spellcasters, and will try to influence their summoners' chaotic friends and refuse actions that contradict their programming.
An arbiter who comes across evidence of a significant insurgence of chaos does everything possible to rally its allies against the chaos. If it can't handle the situation, the arbiter will either insist on being helped to reach the nearest greater inevitable, or returning to Axis to make a report.