Great idea and execution! The snappy feel is really satisfying to play with.
I'd suggest that the Clone card show the previously used card in some capacity(like in the card description) since when opponents use cards the order is kinda hard to tell.
Man this series is just a treat, when the mechenics click, they click so hard that my brain feels that rush I so seldomly feel in actual math classes when you feel you're getting ahead of the one coming up with the questions. Good stuff!
This was the coolest thing I've seen in the contest, turnbase and action works quite well, sorta Xcom-y. Also the art and effects are cool af. Thanks for creating this!