First, open the background and insert the moon and other planets (easy too make your self with cloud renders and spherize), then fade the moon and planet using masks.
step 2 of 15
Mask out and rotate your mountain.
step 3 of 15
Add some ice and water along the edge of the mountain. By using a copy of the mountain, desaturate it and invert the colors then use the wind effect, mask away unwanted colors and soften it with the blur tool.
step 4 of 15
Add some mudd to make the shift from the mountain more smooth. (masking it just behind the mountain layer). The shift doesn't look that good yet but there will be clouds that cover it later.
step 5 of 15
Add and mask out our city behind the mountain layer.
step 6 of 15
Lighten the city with some hue/saturation layers, level layer and color balance layer so it fits better with the other layers. (don't forget to mask the effect-layers)
step 7 of 15
Add the upper castle, (just like before; behind the other layers and by masking it).
step 8 of 15
Lighten and change the color appearance of the upper castle with a level-layer (mask it!)
step 9 of 15
Add the flags (paint them with a brush).
step 10 of 15
Lighten all of the "island" on the left hand side so all of the island appears to get the main light from the left. (with a levels effect layer that you fade out with a mask).
step 11 of 15
Now darken the opposite side of the island (use the same method as step 10.)
step 12 of 15
Add rainbow (do a gradient, then bend it and fade it).
step 13 of 15
Add the water, use a brush that fades out and scatters a bit. Add the clouds. Use multiple pictures and fade them out in a mask.
step 14 of 15
Change the whole color appearance so it looks more "natural" (high altitude, more mysterious, etc.), by adding effect layers (hue/saturation and curves).
step 15 of 15
Add the "magic" by drawing shapes. Then you add layer styles, such as inner and outer glow.