The ruins look a bit dark, and the blood pools aswell IMO: you may want to consider the usage of a texture closer to a white or a clear grey to allow it reflects better the lighting
The orange lights look very pale and seem to lack of brightness, they stand out because of their color but not because of their intensity: something to consider to give more 'presence' to the overall scene IMO
Personnally, for such 'cold' atmosphere I prefer using yellow local lights instead of orange ones: yellow is a colder color than orange IMO
Clouds are still far too much ponctual and definitely don't look real: don't take this in the wrong way but they look a bit like some drawings that kids do, where details like this are often too much simplistic to be convincing...
I recommend you take a closer look to the terrain from BR-Icefield or even Bifrost (a cool skybox in this one btw...
) to put more variety in your scene: retail packages present all sorts of snow-covered rocks which will probably fit well your theme