Summoners are agents of the Institute of War. Summoner's work with the champions to fight in matches to decide factions' standings and favor with the Institute of War during Massive Disputes or "Arcs."
Summoners are powerful mages who lend their knowledge and magic to the faction they ally themselves with. In the Fields of Justice, they provide strategic and tactical advice to the champions they mentally bond with, along with their magical abilities. Outside of the League, Summoners give the factions' leaders advice and insight on important decisions relevant to the current dispute.
As agents of the Institute of War, a Summoner's allegiance to a faction is not permanent and usually ends at the end of the dispute. They are then free to work for any faction they choose. However, many Summoners choose to aid certain factions on a regular basis, out of loyalty to a home nation, belief in common ideals, or ties of some other kind.