This is a very clean game, all of it is very well-executed, even stuff like being able to quickly reset when the ending animation plays feels very nice. It almost reminds me of touhou in that way.
One thing i found weird is that theres no music for the shop, it was a little jarring considering the rest of the game has very nice music.
If this were further developed id love to see some more variety in cards, some of them, like the 6x3 and 5x4 cards, feel far too alike to be interesting to get.
Its a fun twist that you are the one with agency over whether monsters get spawned, i was very much expecting monsters just appearing every so often, so seeing that its part of the drawback cards was an interesting take.