I find the idea of battling using the blackjack system intriguing, but at times it can feel a bit like you are stuck trying to win against the casino because of the lack of other tools the player is given apart from getting another card and waiting.
I would have liked a mechanic to play around with the cards you have already been dealt, like the ability to destroy a card sometimes, or maybe swap a card with Hades to try and gain more control over the situation. A bit more than Vanilla blackjack.
Overall, a fun concept that I think could really improve with some more tools for the player to express his creativity