Necklace | The Elder Scrolls | Ouroboros

The Ouroboros is a symbol linked to Satakal, depicted as a circular image portraying a serpent consuming its own tail. Another version of this symbol, featuring three heads resembling an eagle, lion, and dragon, became connected to the Three Banners War.

The Elder Scrolls
The Elder Scrolls Online, commonly abbreviated as ESO, is a massively multiplayer online spin-off of the Elder Scrolls franchise. It takes place in the year 2E 582, making it the earliest-set game in the series.

With the fall of the Reman Dynasty at the end of the First Era, the Dragonfires go out without an emperor to light them. In the absence of a clear leader, three warring factions—the Aldmeri Dominion, the Daggerfall Covenant, and the Ebonheart Pact—use the opportunity to expand their territory, at the expense of their rivals and the residents of the Imperial province of Cyrodiil. The Tharn family (ancestors of the infamous Jagar Tharn) forges an alliance with Mannimarco to assist the depleted and surrounded Imperial Army by reanimating their dead. Secretly, Mannimarco betrays his Imperial allies by assisting the Daedric Prince Molag Bal in invading Tamriel in an attempt to incorporate it into his realm. You are one of Molag Bal's victims, and have had your soul stolen by the Daedric Prince.

The Elder Scrolls (Kelle in the Dragon Language), also called the Aedric Prophecies (though the accuracy of that term is often disputed), are scrolls of unknown origin which simultaneously archive both past and future events. They are described as bits of the Divine made substance so that those within the world could know it, existing at once within, but also beyond and beneath the world, before and after. Though different observers might witness different reflections within the Scrolls, all are true, especially the falsehoods, and many who studied them have been driven to madness.

(from the UESP Wiki)