Nice game! 😄
It was a nice subversion of the card game genre. I was surprised at first to find that I was controlling the character directly.
Maybe the interface could be improved a bit. Sometimes cards being played by the AI were covering up some of the field, so I could not see enemies coming towards me.
Also, maybe you could make the upgrade costs scale a bit. Right now you can easily win by just going for damage every time.
It is a nice game though, I got to the end and defeated the dragon! 🙂