This is addictive! Very fun idea, I really enjoy it. I would suggest to add a number indicating the HP left to each card, so I don't have to remember or make proportion for knowing which card I should target next.
Also, after many fails I think that the only strategy for winning is having a single really strong dice, with two small supports for the second last level, which is a shame becuase the most fun is when you have many dice with different abilities and play wisely each turn.
I really like the option to not play the dice if it has a small number on it to hope in higher result the next turn, really simple yet interesting mechanic. Well done