I'm looking for a long fic set in season 7 that I read a while back. Unfortunately, all I remember is the final battle. I think everyone retreats from the hellmouth during the final battle but Buffy, Spike and Dawn. Dawn is described as the Queen in chess, and Buffy and Spike are the knights protecting her while she defeats the FE. There was also a coven of witches/warlocks surrounding the high school keeping up a force field.
There may have been another scene where Spike was chained up and trapped in a warehouse and left for the sunrise, but Willow and Buffy were able to find him. He may or may not be impervious to sunlight.
I'm sorry I don't have anymore to go on than that, but I haven't read the story in years | 
