Warning: The following text contains spoilers relating to the plot of Prophecies.
The Throne of Pellentia is a throne at the center of the Temple of Ascension deep in the Crystal Desert. When Turai Ossa led the ancient Elonians to the desert seeking to ascend, they built the Temple of Ascension. At its heart was the Throne, where the Chosen would attract the gaze of the Old Gods and hope to be judged worthy of Ascension.
After Turai's demise and the Elonians' failure to ascend, the Temple fell into disrepair. It is now overrun with Forgotten and Enchanted, and the Throne is claimed by the ghost of a usurper. In the Dunes of Despair (mission), the Ghostly Hero leads the players to the Temple, where they clear out the Forgotten and Enchanted in the Temple, and evict the ghostly pretender from the Throne. The gaze of the Gods once again falls upon Ossa and the players.