So everyday I get 3 or 4 free reward cards competing daily quests. Sometimes I get good expensive cards and sometimes I get 2 cents worth of cards. You can get more reward cards if you play at higher leagues and now it's a great time to get in the game because reward card prices went up a lot where you can make decent money by doing daily quests especially if you play at gold, diamond or championship league. You can get even 50-100 usd worth of gold foil legendaries for free which is great for a decentralized card game.
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From @smhunter