Shards of Oblivion
According to the Lord Commander of the Grey Guard, Aureon Lyrander is a crotchety, but powerful, spellcaster. He is a member of the Lyrander family, but left his duties guarding the gate in order to conduct further studies on the elemental chaos and to expand his knowledge.
Arctus realized that Aureon was the author of a few writings on the dark material. Arctus also was able to compare the locations and dates in his writings on experiments to help narrow down Aureon’s most likely current location.