A little bit of an abstract request...I might interpret "battle at the end of the world" a bit differently than you may, and from *my* viewpoint, I don't think many bands of any genre have captured it or explored it very much. A lot of power metal, dark or not, is anthemic and atmospheric in many other ways, lending itself to a whole host of feelings and interpretations, but to me at least that specific seriousness hasn't been touched very much.
I can give you stuff which has a dark tinge and/or is battle-ish, that's about all..
'Prophet of the Last Eclipse' (the song) by Luca Turilli is that some..
part 1:
http://www.youtube.com/watch?v=yBsI60UKP6U
part 2:
http://www.youtube.com/watch?v=edy0fC4WK24