So your PCs have won their quest, be it slaying a mighty dragon with a magical weapon of old, beating a crime boss, or vanquishing a mighty wizard or wight, and they have taken possession of the treasure. Chest after chest of gold and silver coins, gold bars, and every kind of jewel and gemstone is theirs for the taking. If they are not careful, they may find that their trouble has only just begun.
The ochre sands stretch for miles around. Something kicks up the dust. It's a yak. A desert-yak. It ambles slowly, nuzzling the ground for the low-growing shrubs. The ranger freezes. "Stay very still," he warns. "Don't move at all."
"What is it?" you ask, breathlessly.
"It's the most dangerous creature in the whole Ocadian desert. And it's about to eat that yak..."