You carry over armor between rounds and 2/3 enemies don't attack until triggered, so you can just grind indefinitely on any level to automatically win the game. Although, with 2/3 enemies only attacking when triggered, you pretty much automatically win anyhow.
Viewing post in Flower Dungeon [Game Jam Version] comments
I do agree that the game is quite easy. For the most part, I created this as a proof of concept to see if (1) I could create a deck builder with smooth UI and (2) if the growth mechanic had any real potential. Although rebalancing it would improve gameplay, do you feel that the core of the game is solid?
Yes, the core mechanic seems fun-- trading off benefits without growth investment for benefits after investment is a fine mechanic.
I would recommend, however, that either the mechanic is changed so that all growth upgrades, health, armor, and cards in hand reset when moving to a new stage or you add a 'rest' button or something to automate grinding hp, armor, and growth upgrades when there's no danger to the player, though, if possible.