Really liked this! Super good mini version of those auto-battle games. Your pixel art worked fantastically, I know it's hard to get something good with so few pixels.
My only suggestion is clarifying what is yours and what is the hero's. I kept thinking at the start I had moves I could spend, and that I had health or mana. Separating those to the other side of the screen or making labeled boxes with "MONSTERS" and "HERO" might be good