Interesting image with good texture work. What's the source for the flames?

When overlaying an image with textures be careful not to destroy the resolution. (Unless that was your intent). In photoshop, you can see how the tail of the dragon is INSIDE the Castle, but the distance is funked up and gives the feeling the Dragon is flying INFRONT of the castle not landing on top of it. (In my eyes anyway). If that was your intent you may want to burn the edges of the castle where the dragon landed to give it more of grounded/holding the tower feel. Again, this could be caused by the texture overpowering the image and making the detail blur. Only a suggestion as always IMHO.
The Castle source is incredibly blurred in the original source and that adds to the difficulty of matching up the landing effect. Trying to match up the resolution of the castle with the incredible detail of the reptiles cause a lot of the blending issues.
Don't get me wrong, it's a great design, I'm just looking at it as how it could be improved for the overall effect and crank it up a notch.
The calm color scheme is well thought out, but be careful as that can make it a bit bland with no punch. Not a bad thing, but in photoshop there is always room for a little more WOW. GOOD LUCK.