Great job on the game! I love the art, music, and game play.
I ran into some bugs with the deck building I thought I would let you know about though. When upgrading and moving cards I found that after a few actions my cards start disappearing. I would place a card from the lower box to the deck box and it would just disappear. Also on the second to last level I finished upgrading and sorting my deck, went into battle, and found my deck replaced with the default deck from level one, and after loosing and looking at the deck builder again it was still the basic cards.
This was on windows in the Mozilla browser.