Fauna - Rain
If the dictionary played a song when you looked up the word "epic", this would be it. I really should listen to this band a lot more often but I frequently forget they're in my library because their songs are so long and thus I never have very many plays of them on last.fm. There really isn't any other band that sounds like them; there are a lot that have emulated aspects of their sound (Wolves in the Throne Room is the most famous) but no one influenced by them that I'm aware of does sixty-minute black metal songs. (L'Acephale are influenced by them, but their sole ninety-minute song isn't metal at all). In fact the only other black metal songs of comparable length I can think of that aren't by Fauna are Sabbat's "The Dwelling (The Melody of Death Mask)" and Wyrd's "Heathen," which are both awesome songs in their own right but certainly not influenced by Fauna. And speaking of Sabbat, they're another band I need to listen to more.