The Sisters may be found anywhere from street corners, where they offer to tell ones future for a few pennies, to those who appear to be working for the service of a lord. It is said that they go where they will, when they will they work for who they choose, not for who chooses them.
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...