I'm both excited and scared right now: in the novel-in-progress, I have reached the chapter where the climax begins. Like any good epic fantasy, the thing ends in a pretty large battle that actually takes place in two different locales, with the two locales becoming one in the end; and while that battle is taking place, my main character is alone someplace else, achieving her unique mission. (When I describe it like that, the thing sounds disturbingly similar to The Lord of the Rings. Maybe I shouldn't have my heroine having a change of heart on the brink of a volcano....)
The problems that have me worried are pacing and sequence of events. With the denouement transpiring in this way, I have to make sure that I don't intercut from one bit of the action to another at inappropriate moments and that the sequence remains clear. I think I have most of that problem figured out already, as one portion of the battle really isn't initially as important, from the standpoint of the novel's main story, as the other, so that part of the battle can remain in the background, so to speak, until the other battle and the heroine's solitary mission are done. Then the other battle can move to the forefront.
My other concern is to avoid having the whole thing become a morass of dull-to-read carnage. I plan to dip into the battle scenes in Malory, Tolkien, Kay and others as I write this material. If I'm going to steal, I might as well steal from the best, n'est-ce pas?