I am a big fan of Slay the Spire - and your game got the core mechanic pretty much right.
Some suggestions: bring the numbers closer to the hero - having them visually decoupled at the top of screen makes it hard to process them (numbers sitting right on top of the hero inside icons like shield, blood drop or sword would be ideal). And maybe visually support attacks by some kind of wobble or flashing - doesn't need much to let things feel little bit more active.
All in all - cool game!