First of all, the picture is really lovely
Whatever criticism I give is not meant to depreciate the picture, but only to suggest further improvements in future pictures.
As for the positive things I really like the shading of the characters. It is quite tricky to adapt the colors of character to a nighttime scenery and I think you have done really well. Perhaps there could be a few minor corrections about the way some shadows fall (with the major source of light, the full moon being behind Rinkus the shadow still falls in his rear) but these are just small elements.
One thing that I think is a little exaggerated are the glowing eyes of the flyers in the far background. It can happen that eyes reflect light (many will have probably seen the "glowing" in the eyes of a cat when it looks into the light from a dark spot) but I think it looks just a little too strong so the eyes of the flyers look too shiny and a bit too similar to the stars in the background.
One more thing that I think can be improved are the rocks. You took a prepared pattern from photoshop for the structure of the rocks (you did so before), but I think it looks a bit too regular for rocks to look natural. Photoshop has several functions which can work really well for rock or wooden structures. The function Filter > Render > Fibers can create some nice effects. In combination with some own shading (there can be very sharply cut shadows along rocky walls if there is an edge with two parts standing in a different angle towards the light) one can do something really awesome about rocks.
