From a low hillock in a vast plain, the entrance to the Noil Ruins is as unobtrusive as it is a gateway to wonder…
The Pelezians, or “clay people” were strongly bound to the earth. In fertile plains and valleys they lived their happy existence, peaceful, yet ever on their guard. Many nomadic attackers they defeated, until a different enemy came; their advanced technology and weapons (and magic) were beyond the skills of defenders. One-by-one their settlements fell, until the clay people were not more.
To the greedy students of the past, their heritage is but not forgotten.
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.)