Its fluid, its rhythmic and good, very nice but ... i think its very soft for a Boss battle ... i mean, for a stage o a semi-boss its very good but ... for a serious boss battle ... its soft.
But wathever, its very nice the song and i like it .w.
(Sorry if your eyes melted for my bad english, i tried my best to expose my opinion about your song)
Please contact me if you would like to use this in a project. We can discuss the details.