From Destinypedia, the Destiny wiki
Eleusinia is a Throne World that serves as the setting of "The Shattered Throne" Dungeon. It served as a sanctuary for Mara Sov to prevent her death during the onset of the Taken War, with knowledge of the Sword Logic provided by Eris Morn and built with the aid of her Techeuns and Riven. Its entry is accessible through a gateway built beneath the Blind Well in the Dreaming City.
It was desecrated by Oryx, the Taken King during the Taken War, and its corruption began seeping itself into the Dreaming City, cursing it as a result of Riven's last wish. It is also a staging ground for Savathûn's daughter, Dûl Incaru, the Eternal Return, who commands the Taken curse.
List of appearances