Card Master

You can take the magic from any magic item and imbue a playing card with it.

The process takes a long rest and you must have both the magic item and the card with you. Once you are finished, the magic item loses its magic and becomes a mundane object.

The enchanted card works when you take an action to activate it - the cards can be activated in almost any way, as long as you have the intent for the card to be used. Eg throwing it on the ground in a 15 foot radius around you, throwing it at an object or creature, or placing it on the ground, etc.

For example, a card with the magic from a yellow diamond elemental gem would create an earth elemental when activated.