A One-Round Living Greyhawk Principality of Ulek Regional Adventure From the introduction: The Derro have plagued Urgo's Mine and the surrounding areas in the Lortmil Hills for years. Now it's time to put an end to the threat for good. A Principality of Ulek regional adventure for APLs 4-12, and Part 5 and the finale of the Downward series. Note: This adventure will be of particular interest to Mine Rangers and longtime PCs of the Principality of Ulek.