Great idea and a cool mechanic, weakening enemies first then finishing them off. I found it a little bit tricky though, I got quickly overwhelmed at the start. I think a more gradual introduction would be good, starting with just 1 enemy to get used to how to play. I like how you used the sprites for different effects like grass for the shockwaves.
I think with a bit more polish and player feedback this would be a really fun game, as the idea and mechanics are good.