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.
A ruby of immense size, this stone was once the eye of a deity of war. When properly commanded by long lost rituals, the huge gem will rise into the sky, glowing brightly. Visible for miles, all who look upon it in its full radiance will be filled with intense homicidal rage.