You know, I was going to suggest
Powerslave, but I thought it was a tad to melodic for that encounter.
(BTW, I went to see Iron Maiden with Mearls a couple of weeks ago, and it was one of the best concerts I have ever seen. If you love metal, and can get the chance, go see Bruce and the boys -- they do not rock their age

)
The Rouse (and others) is right ,though, you are going to need more songs. I've never heard most of what the Rouse is suggesting (guess I will have to look at his iTunes come Monday) so here are some more suggestions to round it out my original song.
The Mob Rules - Black Sabbath
No Mercy and
Fever Dreams - 300 (Original Motion Picture Soundtrack, cuz that sh**'s Metal!)
Miseria Cantare (The Beginning -- Maybe more "Emo", but I think it works.)
Damage Inc. - Metallica, again.
I would aslo be tempted to put in Rob Zombie's
Dragula...but I don't know if I would actually do it when it came to finalizing the playlist. It might work well as a victory march.
If you are looking for good evocative music to go with your games in general, here are some my current recommendations.
- 300 Soundtrack
- There Will Be Blood Soundtrack (Parts of this soundtrack, especially the tracks
Henry Plainview, There Will Be Blood, and
Proven Lands do a bang up job of helping the DM build tension.)
- The Devil's Rejects Soundtrack (Tyler Bates is a frigg'n genius!)
- Parts of the Lost soundtrack. (
The Eyeland, Getting Ethan, and
Me and My Big Mouth are some of my favorites.)