Very cool game!
Here's some of my thoughts:
I feel like there are too many cards in the starter deck. Also, there isn't a way to view your deck, which is very inconvenient in a rougelike deck building game.
Also, enemy attack transforming your cards is a cool mechanic. However, changing too much cards into enemy type cards might disable player from having a consistent strategety, forcing them to play with whatever they currently got on hand. Maybe the card transformation can happen after the combat instead?