A solid card game.
You fit the theme into this concept really well.
I like the concept of waiting turns until the card is activated. This creates a new layer of strategy. It wasn't too overwhelming as a new player.
The only thing that I would do different is the display of action.
The "Choose attacker"- and "Choose target"-display disable all the input for 1 second and it feels unnatural if you can say that. In this case it would be better if the text was in a corner and would be shown the whole time until you selected an attacker or a target but doesn't disable input. (I hope I brought across the idea correctly)
Other than that. No complains. Good game. Had fun. :-)