It's a lot of fun to play, but it does have some flaws. Mainly, it's too lucky. Right now, the optimal way to play is to keep restarting until you can beat level one in one move, which requires you to get a cantrip or splash in your starting hand, and then either another cantrip or a rook/knight, or both, depending on if you get the yellow or blighted capybara. Then, you want to restart if the first shop doesn't have an affordable cantrip. The random draw combines poorly with the countdown mechanic within this sort of tight gameplay, especially with such an all-important upgrade store. If I was designing this, I'd add some kind of draw mitigation mechanic, such as a mulligan or discard-and-draw option. Despite this, I ended up playing it several times, and beating it a few times, too.
I have to concur with what someone said below, that this would work really well in a larger setting, such as a dungeon. I can see some potential for a Bindinf of Isaac-style dungeon crawler.
 "Pawnbarian"){kind=icon}
 "Tales of Nebezem: Golden Scepter"){kind=icon}
 "Polygonal Fury"){kind=icon}
Cool, I hope you'll enjoy it!