A small, primitive village has yet to discover fire, which is a good thing because there are highly flammable (but not otherwise dangerous) gasses in the air. The heroes, blissful in their ignorance, don't know that and think it a wonderful idea to show the locals open flame.
Unbeknownest to the character, he is in the royal bllodline. Suddenly the majority of royals fall ill and die, and the hero is left with the crown, but no experience or idea of what to do.
A Deity of some sort has unleashed a plague of bookworms or something like that in the area. Almost all spellbooks are destroyed, along with bardic and historical books.
Mages/ wizards and such use cards (playing cards or tarot cards) as training tools. The patterns created by certain layouts of cards are mnemonic devices to teach key elemental associations and paths. With such interesting names as the Tree of Life, Phoenix's tail, Rythm of Heart, and Balance of the sphere, there pattern represent the matrices used by magic users to focus and present power. Spell processes can be represented by a sequence of cards.
So mages will often be seen handing around hands of cards.
Wizards will have a deck of cards with them. Since cards were used to train wizards in legerdemain, Since they have cards with them, they frequently know how to use them. Guild magic users often have a knack for fancy shuffles, palming cards, and a variety of card tricks and games.