Tough one for non-spoilers, but I'll try, as it's a neat question, I think!
Well, there is some imagery late in the novel that came together very gradually and organically and I was happy with the subtlety of it. It wasn't like I was slathering it on, but the imagery was just insinuating itself and I was there to expedite it. Further (and this has happened in most all my longer works) this imagery involves secondary characters, none of whom were planned out when I started - I just realized as I went that I needed someone for my main characters to interact with, I came up with some who seemed interesting and believable, and they took on a life of their own.
Now, it's even harder to describe the scene I don't like w/o spoilers! But, well, I have revealed before that a major character dies, and it was hard for me to block that scene in a way that I felt was sufficiently suspenseful and tense. But, I'll let it simmer and look it over again when you get to it, and I think it'll turn out great by the final version!