Legend Lore: Gulthias, the Dream Architect

Long ago, at the height of the Oshran Empire, Vulwin Dorren enacted great feats with the Dream Matrix he wielded. Using the Legend of a Beholder, Vulwin dreamt of a one, and brought it into existence. Vulwin invoked the Matrix to put the Beholder to sleep, and named him Gulthias, the Dream Architect.
Within the Gleaming Halls that spanned all of Idriell, Vulwin put Gulthias to use, making the beholders dreams become reality, and Vulwin's power grew a hundred-fold.
As the Oshran Empire began to fall, the few elves that retained their Selves sought to repurpose the The Gleaming Halls to imprison a powerful seducer; Rohini. Rohini proved to be more powerful than any strength the Oshrans had, and so they decided to close the Gleaming Gates, with Rohini trapped inside. With Umbral Blood, they sealed the five entrances to the Gleaming Halls, turning it to a prison. Gulthias was left to ensure anyone who tried to walk the Halls would face a series of trials designed to prove they were able to handle Rohini.
But Rohini's influence was more than the Oshrans anticipated. Her corrupting influence spread, to the Gleaming Dungeon, its Wardens, Keepers and Architect; and through Gulthias, spreads into Idriell once more. Pretenders, Nightmares, Blights, and other Shapechangers attempt to subvert and corrupt the world at large.
While Gulthias sleeps, he believes he is the Pretender, and the Pretender exerts Rohini's will, and the will of [XX].