Speak to Orus'Dakh, located in the Residence Court at ( -349, -10, 508 ) Copy/waypoint -349, -10, 508.
If he is absent, you can summon him by inspecting the monolith while carrying the following runes that spell his name: orus, duak, ahk, kan, and hek.
The first of these, Orus, has been reported to drop from shriveled mummies (also found on "a mummy") in Sinking Sands. The others drop commonly from zombies throughout Living Tombs and Sinking Sands. Check you have all of the runes before you start putting them in the monolith, as it will not give them back to you if you are missing any.
Pick up the following artifacts within the Residence Court in The Living Tombs (these items pop and depop randomly, every few minutes; be patient):
a bucket of spoiled meat at ( -278, -5, 350 ) Copy/waypoint -278, -5, 350 or ( -280, -5, 408 ) Copy/waypoint -280, -5, 408
a bottle of spoiled wine at ( -302, 19, 423 ) Copy/waypoint -302, 19, 423 or ( -380, 4, 425 ) Copy/waypoint -380, 4, 425