They're All Dragons in the Extra Deck, and You Call That a Hero Deck?

(The duels in this story lean toward OCG, but with unlimited Extra Deck cards. Some characters from the Asahi version and the manga will appear, though quite a few have been changed.) After transmigrating into DM, all I have is an incomplete Elemental HERO deck. But the System's support is suspicious. Explain this to me: what do you mean a stage fit for HERO battles is called "Primordial Stone King's Vein"? Is that really okay?