The Tattered are driven by hatred. All their lives they have done without, and given a chance to close in on those who ‘have’ they kill with disturbing intensity.
Via Humanitae - For Humans to live and thrive, non humans must be removed.
This organization began with a simple idea to protect the common people from the danger of magic run amok. Far too many disasters and atrocities were being commited by irresponcibe, evil, or mad wizards with no one to answer to but their own degraded consciences. But like so many things, it started off good and has shifted to the dark side.
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.)