This is pretty good! I got through easy and normal, but hard mode got me quite a few times before I gave up. The AI seems to unlock their king-variant pretty fast and once that happened, anything I did failed to make a difference. I've seen the tips, but I only saw the one about tall slimes being strong against warriors, which seemed to repeat every time. Though, I may have simply missed the others. I wish the tips stayed on the screen longer, or that the game would scroll through these on the main menu or something so I could just see all the hints.
Other than that, the game is basically a knockout! Great job.