“ Made from the tears of a bound goddess, this magical wine has the power to charm or dominate any who imbibe even the faintest quantity. Once affected, it remains dormant until the victim hears a special magical phrase, upon which they will be magically bound to the speaker. Enterprising villains could drop this into the water supply of an important city..”
“ Temple of some malign being invites you warmly and offers help (curing,needed spell etc) for some minor sacrifice . Sacrifices must be everytime bigger to work - up to living inteligent creatures. Maybe you pay some other price,too...”
“ 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.)”