From Iji, a freeware game.
None of that chanting vocals or awful lyrics stuff; just good, inspiring rock music that gives you the feel of a world just on the knife's edge of disaster (and appropriately, this battle takes place minutes before all of Earth is going to be nuked into oblivion)
I will agree with the OP that that music is really good. Might be relying a bit too much on the standard holy-chanting theme, but it has good rhythm.
Also: Trying to take the time to listen to most of the tracks here, but most are really good, so I'm not sure which to spend more of my time on...I like that so many of them have a certain buildup to the climactic portions of the fight. Works well for RPGs which tend to have some leading dialogue, or it takes a few turns of combat before you really feel the tension.
Goddamn, this makes me feel so tired of how most newer games, especially FPS's, haven't bothered giving you any sort of boss fight or even any large direct personal conflict with one character.