Elephants crossing the seas!
It is not an infectious disease, but it is a plague upon the world.
For it spawns villains. And not your garden variety villains, but epic villains, master villains of the most dangerous kind Evil Geniuses.
Pnathic sorcery has existed for ages, crudely used by magi who no idea the true forces they were fumbling with.
An article concerning the nature and role of druids in an RPG enviroment.
Plagues and other great diseases are important parts of history and some settings. They defy man and may even defy God in their swift and terrible punishment upon the body of society.
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.