“ 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.”
“ A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for study by the Guild. The party's presence will be 'requested' for this expedition.”