The Worldslayer Chronicle
The Lost City of Ne Koph deep in the desert of Osirion was destroyed millenia ago by a curse unleashed by a demilich. The Demilich was sealed away by a group of Sarenrae clerics and sealed beneath an Inverted pyramid.
The power of the demilich was so great that the plague of undead continued, causing the people of Ne Koph to eventually abandon the city.
Recently a group of adventurers dared the dangers of the city and the many traps of the inverted pyramid and released the demilich.