Speak with Tolfdir in the Hall of the Elements and he will marvel at the Eye of Magnus that the College retrieved from Saarthal. He will say that the markings on it are of a kind that they have never before encountered, and that they appear to be neither Elven, Daedric, or Ayleid in origin.
Ancano will interrupt your discussion and ask you to follow him to meet a mysterious visitor who has asked to speak with you. Follow Ancano to the Arch-Mage’s quarters and you will meet Quaranir, another representative from the Psijic Order (the first you encountered was Nerien, who appeared to you in a vision during the Under Saarthal quest).
This Quaranir will freeze time around you and begin speaking to you in secrecy, so that the other two cannot hear what is said. He will explain that you must prevent anyone from using the Eye of Magnus, as “the world is not yet ready for such power.” He suggests that you seek out the Augur of Dunlain, who can be found somewhere within the college and may be able to give you better guidance.
As your conversation with him finishes and time returns to normal, Ancano and the Arch-Mage will appear confused as they will be unsure of what just happened. Ancano will become highly suspicious of you and the monk and warns that he will eventually figure out what’s going on.
Speaking to the various mages around the college about the Augur will usually direct you to either Tolfdir or Mirabelle Ervine for more information. You can either [Persuade] Mirabelle to tell you where the Augur is, or talk to Tolfdir, who will reveal the location immediately. He will also fill you in with some background information about the Augur. Either way, you learn that the Augur can be found in The Midden.
You can access The Midden from a trap door in the northern corner of the College’s courtyard, or by a stairwell in the Hall of Countenance. Making your way to the Augur of Dunlain is relatively straightforward, but you will encounter a few Ice Wraiths and Frostbite Spiders along with a small number of undead such as Draugr or skeletons. If you have received the quest J’zargo’s Experiment, this is an ideal place to complete it by using his Flame Cloak scrolls against the undead enemies that are vulnerable to fire.
Perhaps The Midden’s most interesting feature is the the Atronach Forge, found on a lower level near a door leading to the Midden Dark zone. This facility produces various kinds of magical effects and items, the most powerful of which are available only to players with a Conjuration skill of 90+.
Proceed into the Midden Dark, making sure to locate and pick up an Alchemy skill book which you’ll find sitting on an alchemy table. Eventually you will reach a door. As you approach it, the Augur will warn you from the other side that your efforts will only end in disappointment. The door will then open.
The Augur, appearing as a radiant orb, will inform you that others have sought the Eye of Magnus before you and have thereby met their ruin. Ancano is searching for the key to its power as well, and you are told that your paths will cross. The Augur will inform you that The Staff of Magnus is required to avoid the “disaster of which you are not yet aware.” You are directed to inform the Arch-Mage (Savos Aren) that the Staff is needed, and then The Auger will vanish.
You will likely find Savos Aren in the Hall of the Elements with The Eye of Magnus. Informing him of what you have learned will complete the quest. You are rewarded with a leveled item called the Mage’s Circlet.