Put some source images on the path. Notice that I won't use the source of the knight in the last result.

Start to draw the clouds around the castle. I used soft, scatter brush to draw them.

More cloud

Put more real cloud from the source to the right side of the sky

Blend more cloud from other source, use soft brush to erase the edge or overlapping area

"convert" the castle to the golden one by paint over. I used clipping mask on the layer of the castle, use the overlay blending option and paint with yellow color

Paint the light from every gate, windows... by white soft brush on a layer above the castle layer, use Normal Blending Option

Finish painting the Phoenix

Change the dress of the white fairy: duplicate the bottom part of the dress, use Puppet Warp tool to bend it, blend it back to the original layer by eraser (make it transparent). Repeat twice.

Paint over with sparkling brush and soft brush to make the light and dust on the dress

Make the wings of the bird moving by selecting the wing ares, duplicate, moving blur, blend back to the original layer (for half of the wings). Repeat with the other halve, choose the moving blur by other direction, blend back by eraser.
For the pegasus, paint over on a clipping mask to make it golden, fix the shadow and light by brush. Duplicate the wings, use the radial blur filter. Repeat one more time. Merge the wings layers, then use the invert color to have to blue color. Duplicate and flip the finished pegasus

Put remaining sources to the image (the birds were drawn from last step with the bird brush set). It took quite a long time to extract all of the sources.

The same strategy was use to fix each of the source to the scene: make clipping mask (overlay setting), use soft black and white brush to change to lighting and shadow on the object) --> make one more clipping mask (multiply setting) to make the shadow, use the darkest color on the object to paint) --> draw the shadow on the ground by a layer on the ground layer, use Multiply setting and paint with brush.

NOTICE: there are several light sources in this image: from the natural light, from the flying castle, cloud, from the glowing fairies. The light from the white fairy makes the shadows on the child and the animals go to 2 opposite direction, the fairy herself almost has no shadow because she is the light source.

Finish "fixing" all the sources. Change the light distribution on the ground by paint over with overlay mode. Notice that the ground area on the foot of the horse on the right is dark, but its leg is bright, so I blend a bright area of the grass to this place. The far scene around the elephant was brighten because the animals are bright. Use Gaussian blur to make the animals have the same blurry level as the part of the scene they are on

Make the wings for the dragon by duplicating the small "wings" on his back many times ;).
In the last step, I made a top layer with overlay setting to adjust the light on the whole image, make some light beams from the clouds...
The overall vibrate level was increase