 Tolkien's "The Lord of the Rings", Lloyd Alexander's "The Prydain Chronicles", and Terry Brooks's early "Shannara" books.The structural formula is described by Thompson as that of an Aristotelian trilogy, with each volume representing one of three acts of a larger story arc.The name of the series stems from the "Swords of Asahiel"--described within the story as legendary talismans endowed with a divine fire, wielded by god-like "avatars" in the forging of the earth.