Once again not mine, but amazingly captured by a youtube team that apparently captures a lot of Boss battles.
Lets start with the video before I share their channel
As usual, want to watch it in slomo? go here: http://www.youtubeslow.com/
Creator of video: https://www.youtube.com/user/DavidTheBarbarian1 which has loads of bossfights, and since both player and enemies often go all out during said fights, it might be a wealth of other inspirational content