“ You find a patch of edible funghi. They taste well and all, no ill effects. UNLESS you consume some beverage, even 3 (three) days after eating it. Then you become really sick with pains, vomiting, all the fancy stuff. As a gift or good meal, it could be a cruel joke or to make sure the heroes spend their time focused on the mission. And the fine soup you had in the inn yesterday could have some in.
(Inspired through a real-world fungus. Was really used to cure alcoholism.)”
“ Village has a nearby natural substance that comes from the ground and burns well when lit. They use it only locally and try not to let the secret get out.”
“ The Hierophant of Greenmarch is a lycanthrope. Rather than seeking a cure, or hiding his condition, he considers it a blessing from the Goddess of the moon, and requires that all of the Druids and loyal Rangers of Greenmarch to share in his gift.”