It took me a few tries before I really understood what to do (in particular, I naively thought that if I put on the right color, I wouldn't take the damage), but it was a lot of fun to play from then on! However, I think there's a visualization problem: I often have trouble finding the damage box, especially when it appears below me :(
Otherwise, I seem to have attacked the mages well (with their heads straight out of a boxing match), but after a while their attacks literally take up the whole screen :'( I didn't beat any of them as a result.