Time to throw my votes in here, always happy to see good entries! Voting was even harder than usual this time.
Tremendouz: Ominous and thunderous, very cool! I can see this perfectly fit your setting. Love the countermelody at 1:39 too.
Shrinx: Welcome back! I really see a huge monster here, in a kind of 3d rpg, very cool vibe. There is a low note that sounds a bit weird to me towards the end, but not enough to ruin the track
LordMev: Metal lends very well for a boss theme, I like how the song works.
hlesperance: As much as I'm enjoying this piece, I couldn't picture it on a boss fight. It sounds more like a prologue to me, or in any case a track to go together with someone telling a story. Nonetheless, the structure of it is really nice, and it is as always full of cool ideas.
Floflo: James Hetfield would be proud, energetic and driving, go around and shoot everything.
SharpRainMusic: You're in the suburbs, a pointy-haired DJ comes there and say that he can play better music than you. You lose it and you start a techno fight to show who's the boss. Nice choice of synths and good production, this sounds very cool.
Avaruussaha: A bit rougher around the edges than your usual, but the piece is very cool. Variegate, dynamic and with a lot of character, definitely a great compositional work.
Mairiba: Definitely gives the feel of a mindful and smart opponent, sort of mafia-ish game, I picture the guy to be a classy oriental hitman for some reason. It is very Mairiba too.
My top 3:
[3rd Place] Tremendouz
[2nd Place] Avauussaha
[1st Place] Mairiba