Magical curses are rarely cast, as if cast on someone for fun or purely maliciously and the person cursed has not done something seriously wrong, it tends to ricochet back on the curser. Therefore the few who do get cursed are shunned by most people as genuinely guilty,and few will help them.
The words of a wedding vow contain a strong love spell which enchants both the people who says it, so they will allways be deeply in love with each other.
Little halflings are told that if they don't behave, a demon called Santa Claus from a hell of ice will kidnap them and force them to toil making toys.
The Lord of the Flies, the Muscimancer has studied magics that summon, control and otherwise deal with flies. The Fly Mage is an unwholesome character, also likely to have magics of disease, rot and pestilence up his sleeves. After fighting through his swarms of flies and his loyal acolytes and slaves, the Muscimancer reveals his final power, transforming into a giant half man half fly hybrid. He can fly, acid vomit, as well as continue to use spells, wield weaponry and command his swarms.