I've listened to the track, it doesn't give serious nor tense vibe (expected from boss battle track) but it gives grandness vibe (like being in grand palace, throne or something).

listened to the tune and really liked it very nice melody i make sometimes also tunes

My first association is that this plays when some exposition is happening, and maybe we're having a bit of a scripted boss fight etc. because the slower tempo would support something like that. I think it would be cool to introduce a new element for the 2nd half, like a guitar solo or something that would be in contrast to the very measured and harmonic base you have here.