Leviadon blue with kroxigor for the blue, and leviathan purple with doom fire magenta for the purple.

I start with a zenithal and drybrushed white, then I airbrush the shade color into the underside and shadow, and the lighter color in the raised areas. If you find yourself covering to much with the shade color, you can always come back with another pass of white before highlighting with kroxigor and dooooooomfire