Kueh-Ku was a vicious and evil person.
During a mission, Kueh-Ku acquired a strange black gem that somehow burrowed its way into her flesh, buried in the center of her left palm. This gem absorbed all magic cast against Kueh-Ku but also made her unable to use magic items. Nobody knew if the gem was a sort of ioun stone and would burn out or if it was a permanent power. Initially, she tried to get it removed but soon found it very useful.