Taking desperate measures, the ulitharid Thalynsar transformed himself and several other illithids, including Tsurlanej, into liches so they could devour the elder brain, preserve its knowledge and powers, and take its place. Successful in their endeavor, the illithiliches formed a Conclave of Elders, with Thalynsar as the most powerful among them. He tried to retain much of the elder brain's knowledge for himself, but the excessive information steadily turned him insane.
Nevertheless, Thalynsar ruled Ch'Chitl for over a hundred years. Finally, around 1370 DR, Tsurlanej and the other Elders united and were obligated to kill the insane Thalynsar. However, they struggled to lead in his place and divide the elder brain's lore. Tsurlanej rose to become the new leader of the Conclave.