I totally agree with Blue Lava that you shouldn't have fun with this boss.
Very dark atmosphere, I love the sound of the clean guitar and its melodic line at 1'10".
As I'm not at all a metalhead, I don't know if it's a « classic » thing, but from 0'38" to 0'50", you play the snare on 3, then on 4. It threw me. It gave the impression of being somewhere other than 4/4. It makes the music a bit elusive, which is great for a boss.
And where did you find the whisper for the outro ?