Long has the question of truth been pondered. Long has this been a folly few recognise in time. A killer, a soldier even with a sword is one thing. But a killer who thinks he has found a definite truth, which he decides to fight for, is the most dangerous man in the world.
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.