I didn't think this felt "epic", whatever that's supposed to mean. I'm not sure what the battle itself is, but a generic boss battle would more or less go with this song.
Fitting, at the very least
It's a good song, don't doubt me there.
Has that sensation of epicness in there, and it's a good final boss fight.
The beginning is slow- allows the boss to use those easy attacks first, or the introduction scene of the character- then speeds up a bit - giving the sensation of a rough band of attacks are on the way- then the main part -fully blown out.
It's fast, which is another good thing, gives the sense of excitement and peril.
However, there is a few things that you should consider when putting this in the game:
Have the intro be as is, but find a way to make the last part a bit longer, and also smoothly loop.
Perhaps a bit more guitar, and or maybe shift the pitch down a bit, would make it sound deeper and thus even more terrifying.
On the last note, though make sure that the sound is all good, no sense in it being epic when you can't hear a thing! XD
otherwise, maybe a bit more hectic and really get that sense of terror in there.
Good job though, I look forward to playing this game :)
Please contact me if you would like to use this in a project. We can discuss the details.