I really fell in love with the idea. A lot of people already know the different kinds of combinations so those people can very quickly get into a game with a somewhat complex mechanic. This combat allows for players to come up with clever optimization tactics of how the hand and and playing field can be best used to deal the most damage as possible as safely (easy to execute) as possible. Oh yeah that's the good stuff. I did not think however this game executed it well. Once you find the powerful staff I couldn't get bothered to look at my hand and multitask and just ended up spamming the '1' button to drop random cards. Having the staff made the game easy enough to defeat all enemies with this strategy.
I also tried to beat the dragon without the super duper staff and it was just frustrating as the bullets were too fast to dodge and the reward for getting rare combinations didn't seem great (maybe that's a glitch, I thought I saw a 4 of a kind recognized as a 2 pair but not sure it happened so fast). It should be reinforced very strongly that making better poker combinations are the easier way to win, since player will naturally do what seems more easy.
It is fine to make a difficult game but it should feel more fair. There was just no way for me to react to the hellfire from above.
The movement also annoyed me a bit. The character moves on a grid which reminded me of the game baba is you, which is a game where the character moves from tile to tile as fast as the player can hit the arrow keys. Being slowed down took away from the juicynes. I'm guessing this is done for the combat system to limit the dodging capabilities of the player but bullets fly so fast that it would seem better to me to unlock the character speed.
I could definitely feel some of your Undertale inspiration in the dialogue and it was nice. It really added some character to the world. I really liked the characters in that game and how they're so lovable eventhough they are the bosses that you are tryin to kill. It feels fitting fitting for this type of game.
It was very interesting, and I'd love to see an improved version of this game. good job