A rare branch of the arcane masters, encountered only among the deepest hill folk or ramshackle cabins, the Saucerer takes his power directly from the consumption of cheap liquor. Only the strongest, rankest, most nauseating of homebrewed alcohol will do, where it is instantly converted into mana available to the caster. Without a minimum level of inebriation, the Saucerer will be unable to cast any spells, as focus inhibits his spellcasting abilities.
A man has been committed to an asylum for schizophrenia. The doctors are convinced that he is suffering from delusions and hallucinations. The reality: His soul has been split among three bodies, each in a different dimension, and he occasionally feels and sees what his other "selves" do.
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.)