I think the lightsource inside the eye sockets look separate from the skull itself, since it doesn't seem to interact with it. It makes an otherwise cool looking skull look cheap. I'd make the glowing eyes point bright pixels, and do some funky lighting to show the insides of the eye sockets, mixing the light orange of the light and the green of the shadows.
Also, the forehead rune looks imposed on the image, not painted on the skull nor engraved on it. Light interaction again *hint hint*
Palette and anatomy are nice.