Dark Citadel - stage 3

I've put in the basic Tonal Underpainting now but things won't start to make sense until I get some colour on it as it's all about the lighting. I know what I want it to look like but there is a lot of invention to come in when I start painting each area. I will start with the sky tomorrow and then the background mountains...
Burnt Sienna and Winsor Violet thinned with Liquin applied with a rag.