With a guitar or higher-level weapon, if you hit him straight upwards with a killer shot, he will fall down and collapse instantly when you die. Since you will hit him over 2000 feet, he will come falling down with a flame shield. The flame shield remains around him when he walks away.
"challenging" level is so hard that I can't even begin to imagine how hard Legendary must be. It's much too hard, but otherwise a good enough game. 3/5