The screenshotted early encounter below is not fun — on most turns the enemy heals faster than I can damage it and its health pool is so large that I have to get lucky with my damage output multiple turns in a row to beat it. Perhaps you could introduce some additional health scaling on enemies or a lower tier of this enemy so that early fights against it aren't quite so tedious.
The same dynamic is also true of multi-enemy fights on later floors where shielding/healing can turn them into huge grinds or just make them feel unfair — two heavy hitting shield enemies and a move-copier for instance, if you aren't able to take the move-copier out on your first turn.