I agree with others that the pacing could be a bit quicker. I managed to kill the 4 star enemy next to the first sombrero wearing skull on the map, but it took a long time because of their little healing dance and shields.
I like how you run out of ammo but I think reloading shouldn’t be tied to a card. Just let the player reload but it costs them a turn of inactivity. If you let the player use all their cards on a single turn, then the decision of when to reload would be important as you might find yourself unable to use your more powerful cards due to a lack of ammo.
This would make the game more offense focused and faster paced as the player could unload on the enemy. You might need to create a more in depth deck building system for this to balance the combat though.
This was a cool idea and definitely one of the most unique entries