(Psi)SeveredHead
Adventurer
If the PCs get lost and thirsty, you could have an oasis. Naturally, the oasis is an illusion, and it's actually a trap filled with life-sucking plant roots, or "fake" water that traps anyone who tries to pick it up or drink it underneath itself to suffocate them... or something. And that's not taking into account the sand brides, sand witches, or what have you that live there.