This is NOT a stub, it's all we the information we currently have on the subject.
The Ythol Annulus is an artifact that contains all the mana that is or will be from the plane of Ythol. Physically it is a flat, circular ring about two feet in outer diameter, made of a dull grey stone with an inlay of opalescent crystal. Its creation was masterminded by Dantalion, during the reign of the Last King of Ythol. It was broken into three parts and hidden on three different worlds after Dantalion was confronted and defeated by Kala, Ilyria, Bar-Sagrum, and Vyntiria. It was brought back together during Phantoms of the Past and is now in the possession of The Tattered King. In theory, the Annulus grants its wielder nearly infinite raw power.