I really appreciate the determination in this song! I could definitely picture this being around a boss battle.
I will say though, while I was listening my ears were having trouble "resting" on any one part. I think this is because the melody and the accompaniment are clashing against eachother fighting for attention. I would love to see more clarity with the melody!
One thing I do appreciate are the bell-ish sounds that are sprinkled throughout. They are a really nice addition for hinting at the Halloween theme you are going for.
Nice work with this.