Wow this is a great piece of artwork and captures that haunted feeling right down to each detail. The erie way you drew the shadows of trees and the use of fog effects make you really feel this is creepy and perfect for a haunted setting. The blues and cool colors really make it seem haunted too because it isnt using bright happy colors. Good choice there. I would say this needs some characters but you said it was a background for a piece you are doing. I look forward to seeing this from you.
~~THINGS TO IMPROVE ON~~
I am just looking forward to when you add some characters. Good job overall.