Final Boss Battle Theme

This is my first time making this kind of music so any comments and feedbacks are appreciated!

@JSTM

I think that it could work if:
1. you made it longer:
look up other boss fight ost-s, a boss fight is usually long and you should keep the player's interest, which brings me to my second point.

2. add variety:
if you'd want to use it one day for an actual game, people would have to listen to it looping for a long time.

How long are you able to listen to it on loop? How would you feel fighting a boss listening to this loop?
3. I personally feel that it could benefit from a louder, stronger, bass line. 

this sounds more like trailer music than a boss theme. I agree with Rabbival on some points

1. It is short and needs to be much longer (maybe 3 or even 4 minutes)

2. Repetition is not necessarily a bad thing (see the boss fight themes from Yasunori Mitsuda in Xenosaga). That being said, it needs to go in a direction that keeps it interesting. one thing to note about Mitsuda's boss fight theme is that it doesn't build up for several minutes, it's very intentional for when it gets loud and builds and delays it enough to where the loop doesn't become a "not again moment."

3. Related to number 2, I don't know if the bass line needs to be louder and stronger, at least for a boss fight, but for a piece like this that sounds more like a cutscene or trailer, I think Rabbival is right on it.

First off, I really like a lot of what you've got here, though as the others have mentioned, some things could be improved.

1. Adding more structure to the song. This feels a lot like one loop that is simply repeated and expanded upon throughout the whole song. This is NOT always a bad thing, especially if it's going in an actual game and may need to be repeated a number of times to fill the entire length of the boss battle. However, it can lead to a more stale sounding piece and be quite boring if listened to on loop. My personal style would be to start off strong, quiet down a bit, and then rise back up again with the intensity of the song. Fit the mood and structure of the song to fit the dynamic of whatever the fight is suppose to be.

2. More instruments/depth. I like the intensity of the last 1/3 of the song, but the beginning feels empty in comparison. If you want it to feel tense and hollow at the beginning, add some soft strings, woodwinds, and tuned percussion in the background to give it a bit more depth.

3. Experiment with what you like! Trying new genres is fun and exciting, so mess around and see what you do and don't like when writing music. Listen to songs that are similar to what you're going for and note what you do and don't like.

Probably the biggest issue here is that it is clipping/slamming the limiter. Turn it down.

The other thing, musically, is a lack of any real bassline, but this is a ubiquitous problem in modern cinematic music.

The piece lacks forward drive and momentum because there really isn't any sort of pulsation from a bass instrument. If your lowend is slow or you have no bass part at all, it doesn't matter how fast the drums are going, the violas are sawing or the winds are whirling — the entire thing will lack drive.

Which is important in an epic battle.