Just played one round of your game - got defeated a little after "three boss monsters" entered the game, your core loop at the moment feels good, but not excellent, since decesions so far "feel to simple".
There is one issue with "healing up"... with two monsters i always focussed on slashing one first and then "stack defence" and only continue "once i'm fully healed up" again. So it didn't matter how strong the monsters are... i could reliable go into next battle full hp... but it made the gameplay a bit dull (maybe automatic healing up... after a battle might not be a bad idea) ... for 3 opponents the "heal up strategy wasn't working anymore of course"... but this was going from zero difficulty to suddenly impossible.