Really interesting idea! I think there is a lot of potential in being able to customise cards and change stats, and the animations (and monster art!) honestly look pretty clean. It's just a shame that there are a lot of numbers and things to change for each card which can make your strategy on how to win pretty complex, and makes the effect of your actions not feel very significant.
Also towards the end I found out changing a card's health to 10000000 costs 0 mana. Oops :p
I think with some tweaks and more work it could be an actual strategy game. Good job on getting an entry done!!