Another update.
Thanks for the feedback guys, sometimes I cant see the wood for the trees

The fog started as trial and error but as I had made this scene with the camera at 0,0,0 it was easy to position the fog in the preview window.
As regards the fire, yes the fall off is wrong but untill someone works out a
function driven distance shader (that was a hint, hence the bold red

) we have no control over that (I think)
I like the mist, its a bit much in places but I also like the "rays" coming from the Moon ...
Enjoy
C&C
Richard