That's an odd choice. You want people to stop bringing fiat into your ecosystem? Isnt that a far more legitimizing factor than the potential "risk" to the ecosystem? There isnt a world in which 750 DEC was a reasonable price for quest potions. 90% of what you gain is stupid potions you dont even want and even if you did get all cards, odds are they're going to be worth far less than 750 dec combined.