Y'diss was the steward for Count Dravor, a minor noble of northern Tolnedra. Y'diss authorized a force to capture the party on the south side of the Forest of Vordue in a sizable town (maybe Dym in Shelley Shapiro's map).
He had a rasping voice that was almost a hiss, and wore an iridescent and intricately embroidered robe. His head was shaved.
Y'diss, like many Nyissans, appeared to be an expert at pharmacology and administered several different substances. He was using these substances to drug Count Dravor so that he could administer Dravor's affairs. He was actually acting on behalf of Queen Salmissra and had planned on delivering Garion's party to Salmissra in Sthiss Tor before they escaped.