The Lost Guild is thought long dead by the Arisen at large. They were slain for a betrayal, and took with them their secrets of name magic, and not even whatever relics they have created have resurfaced since Irem's fall.
The Arisen are wrong.
The Akhem-Urtu, Masters of Nomenclature, who bind the seba, the very stars, to their souls still walk this world and will do so for all eternity. They are more monstrous than their cousins from Lost Irem, save those claimed by the only enemy all six Guild share; Ammut the Devourer.
For more information on Those-Who-Deceived, the Book of the Deceived may share more light on these Restless Stars