I ~adore~ (boss) battle themes.
I'm not sure if this is a remix or if it's an original song, but I enjoy this quite a lot because
1) It's not repetitive (unless you count the loop, aha.)
And:
2) It's not DARK (I love dark battle themes, but I think that there's a distinct lack of themes that have different flavours and personalities! (The main reason why I adore all of the boss themes from Undertale, for instance, is because of their varied and novel sounds and structures and meanings and feelings.))
:3
In other news:
The only reason why I didn't give you five stars is because I felt as though parts of the song were not fully expounded upon; I enjoyed the entire song but felt as though a number of parts could have altered the notes ever-so-slightly in order to create both more range in the local part and to also further the actual emotion of the song.