The Asmodeus Mirage

Publisher blurb: Appearing only once a century in the western deserts of Katapesh, the Asmodeus Mirage has plagued Golarion for thousands of years. Powered by a crystal bone devil skeleton and legendary for trapping unwary travelers, the Society has a vested interest in studying and cataloging the source of its power. You have been sent deep into the deserts of northern Garund to enter the Mirage—but there's a catch! The Mirage only exists on Golarion for 24 hours every 100 years. Get trapped in the Mirage, and you may never see Golarion again.