This is a great loop and theme. I can feel the fun and the drama of the fight, its very lively and the melodies and leads are great. Every instrument shines on its own, and it loops really well. I love the little details like the bells and the choir synths, and the solos and riffs are amazing and sound like they are fun to play. I think you've nailed the boss fight feeling and you will certainly achieve higher levels of feels and hype once you put this in the game, regardless of how it looks and plays. Great song, keep the good stuff coming!