Dark Citadel - stage 4

Managed to work on two thirds of the sky today and left the right side alone until tomorrow to mull over what I want to put in there. I'm making it up as I go along as I'm not really working from reference as such, I know the effect I'm looking for and will stop when I've got it.
The colours I used for the sky are pretty simple so far - Phthalocyanine Turquoise, Permanent Orange, Lead Tin Yellow Lemon and Warm White, all Michael Harding paints.