In the 83rd year of the Glory Age, one of the mages of the Nevarran Circle was found practicing forbidden magic. The templars executed him swiftly, but this brewed discontent among the Nevarra Circle. The mages mounted several magical attacks against the templars, vengeance for the executed mage, but the knight-commander was unable to track down which were responsible.
Three months later, the mages summoned a demon and turned it loose against their templar watchers. Demons, however, are not easily controlled. After killing the first wave of templars who tried to contain it, the demon took possession of one of its summoners. The resulting abomination slaughtered templars and mages both before escaping into the countryside.
The grand cleric sent a legion of templars to hunt the fugitive. They killed the abomination a year later, but by that time it had slain 70 people.
Divine Galatea, responding to the catastrophe in Nevarra and hoping to prevent further incidents, granted all the grand clerics of the Chantry the power to purge a Circle entirely if they rule it irredeemable. This Right of Annulment has been performed 17 times in the last 700 years.
—From Of Fires, Circles, and Templars: A History of Magic in the Chantry, by Sister Petrine, Chantry scholar