I just started playing it after a long break. I remember you used to need to upgrade your cards to challenge level in order to be competitive in challenges but

I just started playing it after a long break. I remember you used to need to upgrade your cards to challenge level in order to be competitive in challenges but now they give you all cards in challenge mode at the standard level, even cards you haven't found yet It costs 10 gems to play a challenge and you can buy 500 gems for 5$ so that's 50 challenges, say you get at least 7 games per challenge so 350 games for 5$ where only skill matters. I'd say that's not exploitative. Of course if you care about your rank and having a Big Number in a silly mobile game then yes you either have to play a lot or pay a lot of money.