Thanks for killing 3 hrs of my time. I managed to win finally after multiple retries.
Would be good if the discard message didn't block the view as I want to see the card costs before making any discards. The fonts for 1 and 7 also look too similar.
There might be some slight balancing issues (the sequence of challenges will determine whether you lose or win) and the luck of the draw is certainly high, but on the whole very playable and super fun (5 stars!). Polish this up and I'll certainly buy a mobile game like this as I'm also addicted to deckbuilders.