D&D and Magic are hard-core fantasy brands know by everybody who touches the genre, and for a long time Magic sets have borrowed from the canon of fantasy, and the ancient real-world cultures and their mythology that inspired the first fantasy novels and D&D
Each is a set of two 60-card decks featuring cards specifically designed for new players and an instruction booklet that goes over the games basic rules and cadence of play
This cards ability is often associated with goblins too, so you can kind of picture everyone in the art turning into a goblin for like five seconds
A third possibility, and in my opinion the most likely, is something a lot of redditors are pointing at
These proxies are more than just play figures
From playing with the heroes such as Yuna, Wakka, and Auron, to even finding uses for the minor moments such as the traveling shopkeeper Oaka constantly asking you for money (though in MTG hes after your counters to exchange for drawing more cards)