The Return of the Mages Guild is an chain of events in the Stories of Tamriel. This event takes place in 4E 205, two years since the events of House of Illusion.
A new power dawns on Tamriel. A dark power driven to madness by his affliction. A power that now resides in the mind of a mage called Verus. Notes are sent to those who encountered this force before. The notes simply say "Sorik returns".
During the events of the story, Verus is the Arch-Mage of the new Mages Guild.