One, there's the Audio Adverts thread for this sort of thing.
Two, I think it'd make more sense if you uploaded your music to, I don't know, um... Newgrounds??
Anyway, I took a listen to your track and for a boss battle theme, I guess it depends on context. When the guitars came in, I guess it sounded more like a boss battle but otherwise, it started off underwhelming. And there are some parts which are underwhelming, like 1:03 onwards.
Also, I recognise FL Slayer.
And you, my friend, need to embark on the long hard graft to learn mixing, because these drums are buried behind the rest of your song. I remember being told precisely this when I started using FL, myself, by a number of others on this site, so I'm passing on what I know. I'm also saying this as someone who knows what a battle theme with Sytrus, FPC and Slayer should sound like...