Asmorgal

Asmorgal is a baatezu - more specifically, a pit fiend - that has made periodic forays onto the Prime Material Plane over the past several decades. His purpose on Ardrana is a mystery, but he has been the doom of a number of adventuring parties over the years, most notably Tristan, father of Tristan I of Kellan. He is believed to have a stronghold somewhere in the eastern Onyl Mountains, but it has never been specifically located.