All right, pretty nice dynamics and mood change I like the transitions. I definitely think the percussions could be way more in your face for something that can sound Epic and boss fight, they are pretty far away. Most of the sustained instruments creates alot of mud in the mix so probably some EQ could easily fix this or change some range especially on the brass with the long sustain and couple of chord voicing that are too stacked, open them a bit it will help tremendously. But I like the textures its a nice composition but I think it can sound even bigger.
My comment may seem brutal but since this one is unranked, I'm going all in and trying to give maximum feedback so don't be too offended its still a nice track :)
Impressions Composing Jam: Special Holiday Jam - Personal Project » Entries » The Mountain King Boss Encounter