The PCs encounter an elaborate trap room, designed to fill with water, drowning those inside. Clever and resourceful, they disable the trap and move on.
Only later do they discover that this room is part of the elaborate cooling system that prevents beasts of elemental fire from overrunning the complex. While the fiery beasts run rampant, they begin setting fires, which causes the complex to become increasingly hot and smoke-filled. Additionally, the PCs now have to fight their way out past aggressive fire creatures...
One day a year is the Day of Turning where those on the bottom of the heap for the rest of the year get to live like Kings. Privates question Generals, the people get a say in running things and there is great merriment and gift giving.