Have to throw this random gem back in the fold for newbies passing by. I would generally consider Bolt Thrower one of the founding fathers of Death Metal, because in general that's what the style is. However, in their own way they forged a new genre within a sub-genre with Grindcore, which I think is more of a way to describe a heavier, thicker Death Metal style sound with less emphasis on speed, and lyrics that are not based on an anti-religion, anti-Christian theme.
2 great things about this song, the first obviously is the 50 second intro, which is one of the heavier, more punishing, groovy metal riffs I think I've ever heard. The second is unique to Bolt Thrower and it's just doing something different with something basic. From 3:20 through the end of the song @ 4:22, it seems like your ears are playing tricks on you because the tempo of the song changes several times, but if you listen closely the guitarists just keep churning out the same heavy riff over and over with absolutely no change. It seems like there's so much going on that last minute +, but it's just the same kick-ass riff non stop with everything else changing up around it. Pretty unique, and pretty cool, things like that always set the mighty Bolt Thrower apart from every other similar style band, imo.
BOLT-THROWER Through The Eye Of Terror - YouTube