Great, mysterious chambers hidden deep in the earth beneath that enigmatic city of Stoneholt!
The city of Stoneholt is generally considered one of the Wonders of the World, but it conceals a second wonder - a labyrinth of massive sewers and storm drains greater then anything man has built.
Actually a real-world fungus, just heard about it. A fungus that tastes well and all, no ill effects. UNLESS you consume some beverage, even 3 (three) days after eating it. Then you become really sick, pains, vomiting, all the fancy stuff. Was really used to cure alcoholism. May be a joke or to make sure the heroes spend their time focused on the mission.