Shiznit! I am absolutely blown away by this! I have no clue how I would even go about attempting to make something of this epic kind of quality, other than to hire an orchestra (you know me, acoustic recording all the way...I'm too tech-stupid).
That said, first thing's first: You nailed it. So don't worry about that part. And here's why:
First, the mix is impeccable. Thing just leapt out of my speakers. And they're my crappy built-in laptop speakers!
Second, while the sort of low-pitched dubstep-sounding wubs sounded sort of anachronistic next to the orchestra, for a video game I can think of nothing that brings out just a hint of sci-fi better. If that's not what you were going for, you could possibly get a more orchestral sound with low tympani rolls.
Third, the pace is just right for battle. Gotta hand it to you, often times the most difficult part of getting a song just right is choosing the right tempo.
...I get the feeling that you've done a few of these.
R4R