You also wouldn't think it would be possible to kill a zombie with a card game.
Though with the black magic stuff going around, I think you needed to have one of those things to summon the monster from the card, like how in Egypt you needed one to summon the monster from the stone. So it might be like representational magic. The card carries the image, and if you have one of the Items, you can make it connect to where the monster's sealed.
Or something. I haven't remembered anything with them being around in modern times so it could be just "SO WE MADE CARDS FROM MONSTERS WE FOUND ON THESE STONE SLAB KINDA THINGS" kinda deal.
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Though with the black magic stuff going around, I think you needed to have one of those things to summon the monster from the card, like how in Egypt you needed one to summon the monster from the stone. So it might be like representational magic. The card carries the image, and if you have one of the Items, you can make it connect to where the monster's sealed.
Or something. I haven't remembered anything with them being around in modern times so it could be just "SO WE MADE CARDS FROM MONSTERS WE FOUND ON THESE STONE SLAB KINDA THINGS" kinda deal.