The Black Star

Azura is the Daedric Prince of dawn and dusk. She always appears as female and is considered one of the few  "good" Daedric Princes. Her artifact is known as Azura's Star, a soul gem that can be reused an unlimited number of times.

To begin this quest, simply talk to the innkeeper of any town or city. Travel to the location they will direct you towards, a shrine to the Daedric Prince among the snowy mountaintops south of Winterhold. There you will find a Dunmer, or Dark Elf, named Aranea Ienith. The follower of Azura will speak a cryptic message before directing you towards the inn at Winterhold, The Frozen Hearth. It is here that that you will find the mage Nelacar. At first, he will be resistant to your advances towards information, but a bit of coin or roughness ought to loosen his tongue a bit. Whether you intimidate or bribe him, he will give you a background on soul gems and how they are destroyed after use. He then tells of a story about one Malyn Varen, an old professor at the College of Winterhold and his examination of the legendary artifact known as Azura's Star. Nelacar told of how Malyn descended into madness while attempting to save himself from illness and ultimately grant himself immortality. The experiment eventually escalated to the point where he killed a student as a sort of test subject, resulting in his banishment from the College. He and a few of his disciples fled to what is known as Ilinalta's Deep, a fort half submerged in Lake Ilinalta. This is where you must travel to retrieve the artifact.

Upon arrival at the decrepit and sinking fort, enter through the hatch atop one of the sunken towers. Unsurprisingly, you will find many necromancers and undead waiting for you throughout the dungeon. Kill them all and make your way towards the dead body of Malyn Varen, laying supine in a pool of his own blood. Grab the Star on the chair behind his body and return to the Shrine of Azura. Aranea will tell you to communicate with Azura, who informs you that the Star cannot be used until it is purged of the evil within. She will transport your soul into the Star where you will deal with Varen and his Dremora minions. Once you've killed them all, you will be transported out of the now renewed Star, given Azura's blessing, and the quest will be complete.

(Note: You may bring it to Nelacar, who instead will turn it into The Black Star, capable of holding human souls as well. Regardless, no matter who you choose to bring the Star to, you must confront Valen within)
WC: 452