The Temple of Set

From publisher blurb:

Something foul is lurking beneath the sands of Aegypt, and a horror of the ancient world is about to be reborn

The Temple of Set is an adventure for experienced Rank 5 Mythras Classic Fantasy characters and takes place in the mysterious land of Aegypt, an ancient kingdom of vast deserts, soaring pyramids, and powerful magic. While investigating the disappearance of a nomad clan, the characters uncover a sinister plot that threatens all of Aegypt with unspeakable horrors. The stakes have never been higher as the adventurers face deadly foes in the city of Ombos, brave the haunted wasteland of the Firewind Desert, and finally confront the black evil that festers in the catacombs beneath the ruined temple.