The Staff of Magnus is one of the elder artifacts of Tamriel. It was created by Arch-Mage Magnus, the God of Magic who served Lorkhan in designing Mundus. It served Magnus as a metaphysical battery, but remained behind when the god fled Mundus in the Dawn Era. Since then, it has served mortals. Some believe it was a gift, others say it was stolen, and others believe it to be a test.
In appearance it is a metallic staff, sometimes made of Daedric Ebony, often with a sphere at the end of it. It has the ability to suppress magic, protect its bearer from magical attacks, restore the bearer's health, or allow the bearer to absorb spells. It can also be used offensively as a blunt weapon, and to absorb an enemy's magicka, and eventually their life force. In time, the staff will abandon its owner before he becomes too powerful and upsets the mystical balance it is sworn to protect. The staff can be used to manipulate the Eye of Magnus, although their true relationship is unknown.
By 2E 582, the staff had come into the possession of the Aldmeri Dominion. It was brought to a secure vault in the newly-built city of Marbruk in Greenshade for safekeeping. However, it was then stolen by Vicereeve Pelidil for the Veiled Heritance, who had resurrected the recently deceased Prince Naemon as a lich. Naemon's shade took the staff to Hectahame, an Ayleid ruin where the Heart of Valenwood was kept, and began the process of using the staff to corrupt the Heart. He also used it to subdue ancient wards protecting the ruins from necromancy, which had been put in place long ago after a failed attempt to raise an army of undead there. The Heritance hoped to kill the entire Valenwood by corrupting the Heart, turning it into an evil realm known as Shadow Wood. However, the Dominion were successful in infiltrating the ruins and killing the lich-lord, and the staff was returned to Queen Ayrenn.
The staff was uncovered by the Eternal Champion during the Imperial Simulacrum in either Elsweyr or Valenwood (accounts vary). Some time in the Third Era, the staff was taken from a wizard by the Mages Guild. In death, the wizard's spirit remained bound to Nirn, until one of his descendants sent an adventurer to recover the staff from the Mages Guild. A fake copy of the staff also appeared in the Iliac Bay region before the events of the Warp in the West; it was created by a mage in an attempt to bribe an agent of Nocturnal who has been sent to assassinate him. The fake staff functioned identically to the true artifact, but after several days it crumbled to dust.
By 3E 427, the staff had come into the possession of Dreveni Hlaren, a Dunmer sorceress and summoner. She lived in Assu, a cave on the slopes of Mount Kand, on the island of Vvardenfell. The Mages Guild learned of the artifact's location, and the Nerevarine was sent to slay Dreveni and claim the staff. Later that year, the Nerevarine sold the staff to Torasa Aram, who put it on display in her Museum of Artifacts in Mournhold.
In the Fourth Era, the staff appeared in the possession of an undead Dragon Priest named Morokei, who had, relatively recently, awoken from his ancient slumber. Morokei was entombed in the Labyrinthian, which was once the ancient Nord city of Bromjunaar, the capital of the Dragon Cult. A group of mages from the College of Winterhold journeyed to Labyrinthian to recover the staff, but only Savos Aren survived the ordeal. Aren sacrificed two of his companions to trap Morokei, and sealed the main entrance to the ruins.
In 4E 201, the Synod came to Skyrim in search of artifacts, and attempted to use the Dwemer Oculory in Mzulft to detect magical power. With the aid of a member of the College of Winterhold, a Synod researcher used the Oculory to find the location of the Staff of Magnus, but all other readings were blocked out by the Eye of Magnus which was currently being tampered with in the College. The College member entered Labyrinthian and defeated Morokei. The staff was then used by the College to control the Eye of Magnus until the Psijic Order removed the Eye from Mundus.