Cute frogs! I loved their faces with that dorky lil smile. Like TomatoToaster said, great job working in the frog theme and making it feel like a "frog thing" if that makes sense.
I struggled a bit with the tutorial in the sense that I didn't understand right off the bat that the armor had to be removed before hitting HP, I thought it was more of a "if it has armor use a wizard to target their health, if not use a ninja" deal (but that might be on me for misreading instructions). Once I realized how it worked, I wanted to reorganize my frogs but couldn't move them—a "remove frog" or "swap frogs" mechanic would be cool here. I still won that round (kind of missed having a replay button after the victory message, lol) and my second run went much more smoothly now that I knew to place the wizards first :)
To prevent an easy solution like "put 4 wizards first then 4 ninjas", maybe you could have enemies that have higher armor than usual but very little health so that you'd need more wizards, or enemies that regenerate armor so the player needs to mix wizards and ninjas instead of always keeping them separate. For the debris, because there was no real need to clear them during the game I filled out my board with frogs first and forgot I had to clear the debris strategically only cleared them after I no longer needed to spend flies on frogs. Maybe some kind of pressure on the player (time pressure? Tadpoles getting antsy?) could change that and force the player to make choices to add depth?