I cleared my save and played back to that fight, I died and became unable to hit the red mage again. I did notice however that blood drain restored my hp (its entirely possible I got hit the first time I was playing and draining so my health increased and decreased at the same time). I let myself die again and I became unable to hit the hero either. I do notice that when I attack their characters bounce a tiny bit, but they do not take any damage. I decided to go in one more time after clearing the save data and I know what causes you to be unable to hit them. If you kill either one of them and then die, the fight restarts and at that point, whichever one you had defeated becomes unable to be hit by you. You can also do the fight and kill the one you had not before, and let the untouchable one kill you, and at that point you will not be able to hit either one when the fight restarts again. Also when i was unable to hit the red mage, somtimes he would do his attack animation, and no fireballs would come out. Also I became completely unable to hit them today when I recreated this bug, even though I was able to yesterday, and I can't think of what possibly allowed that. Also I only played in the web browser, and not the download version. I don't know if there's any difference, but I figured I should give all the info possible.