Cards of spells, energy and artifacts are simple enough: Jeup has a mind that already understands how the objects are supposed to work in their respective worlds so in this, they function much the same in terms he defines subconsciously.
The strength of his gift has grown to allow Jeup to access artistic renditions of cards — true or self made — even through digital means. This allows him the ease of using a phone or device to funnel through cards with his will, allowing him to conjure and call out even cards from video games that use them: Final Fantasy Mobius, Hearthstone, Kingdom Hearts and the rest. There is no card-related material that Jeup cannot use to conjure either a creation, an enchantment or a new gift to his requite, permanently.
Along with the creation from card, Jeup can only dismiss the creations with those cards again. Should the orignal card be destroyed then the creation cannot be contained again. Killing a rogue monster would suck so, he avoids ruining the cards.