This is amazing, I love the way the dragon is gripping onto the rock, and the colour scheme is gorgeous. I do think the wings are a bit small for the size of the dragon, but that's just me being a zoologist.
I am very fond of how you have contrasted the beautiful colors in this piece. The dying sunset in the back, the warrior mounted on its beast ready for battle. The whole scene depicts a radiant fantasy scene that is very well captivated.