Pile of Dust  

 

I found 4 ground spawns for Pile of Dust. These respawn at the same points. Respawn time is between 10 and 16 mins.

Locs are in Martyrs passage within Kod'taz

-1318 , 1042 (on the backswall of a small broken building that is next to the big temple.
-1496 , 1101 (between 2 mobs, against the east wall of the passage)
-1823 , 1101 (between a tall firepot and the east wall)
-1818 , 1275 (between fallen piller and the west wall)

Sometimes the mobs next to the ground spawns do not see invis, sometimes they do.

Hope this helps.