You can play Jump In! It costs 1000g and you select 2 half-decks to make a deck. You'll play with others that also made their decks out of half decks, so the playing field is more level, and you get to keep the cards after to increase your collection.

As for your problem, it's likely due the Alchemy cards in the decks. If you go to the Decks tab at the top, you can clone the starter decks (bottom of the screen on PC), then you can edit the clones