Krythkal is the alysaar'vah, a leader of the Alysaar. As of 2503 he was older than Raszagal was, and can still recall Aiur.
Biography
The Past
Hundreds of years before the Great War, Krythkal was a high-ranking alysaar and mentor to a promising young scholar, Ulrezaj. However, Ulrezaj was not satisfied with the simple tasks of an alysaar, and began to access forbidden knowledge. When he was caught, Krythkal begged him to allow his memories to be erased, but Ulrezaj stormed out.
The Preserver's Saga
By 2503 Krythkal was the alysaar'vah, leader of the alysaar and extremely elderly. He was met by Jake Ramsey, a terran archaeologist holding the disembodied spirit of a preserver, Zamara, in his brain. Zamara had an important secret she needed to tell to the protoss, but her presence in Ramsey was killing him. They had brought an extremely pure khaydarin crystal and convinced Krythkal to use alysaar techniques to remove her from Ramsey's brain and store her in the crystal.
During the Battle of Ehlna the Terran Dominion gained the upper hand. Krythkal surrendered the damaged Alys'aril to Valerian Mengsk, who removed some of its memory crystals. Afterward, a protoss force arrived, forcing the Dominion to retreat.
References
Golden, Christie (June 30, 2009). StarCraft: The Dark Templar Saga #3: Twilight. Simon & Schuster (Pocket Star). ISBN 978-0-7434-7129-9.