Pools of Despair

The Pools of Despair are a phenomenon found within the lands of Nehekhara. It is unknown what foul magics spawned their creation, but as a collection of mirages, they have led many to their deaths. It is said that, as one's water supply runs short, a lush oasis will appear. Men are driven mad as they strive to reach these false visions, their canteens filled with what they first perceive as cool water, only to fill themselves with handfuls of sand.

Source

 * Warhammer Armies: Tomb Kings 6th edition pg. 14