A cute little game, I really like the villains downfall being his lack of cards!
In terms of gameplay is very simple, which is not a bad thing, however I feel like nearly every turn the best choice is to just play the highest mana card available to you, which makes the gameplay a bit repetitive. I think stuff like card draw and discard would help add some tactical variety, and I'd recommend speeding up the pace of combat as there's a lot of waiting around.
The art is fairly good and while I think there's room for improvement, it's very consistent and there are a lot of detailed scenes and character designs which is something to be proud of.
Great work.