Basecoat with Mechanicus Standard Grey . I also primed with Mechanicus Standard Grey , to speed things up.

1. Heavily drybrush with Dawnstone . I used a large dedicated drybrush for this step.
2. Drybrush slightly lighter with 1:1 Celestra Grey and Rakarth Flesh . Cover a smaller area, focusing on more exposed parts.
3. Glaze Corvus Black into recesses for shading. Wherever possible, drag your brush with a downward motion on vertical surfaces. This is to help create a bit of a gradient, that will will enhance next.
4. Shade the deepest parts of the recesses with Nuln Oil . Be very selective with this, try to keep to very defined thin cracks and the like.
5. Drybrush with Grey Seer , picking edges, plus corners and points more heavily.
6. Now add a final selective drybrush with White . Go lighter and just try to hit the hardest edges. Feel free to manually add in highlights with a brush, where needed.
7. Using thinned Steel Legion Drab glaze the lower potion of the rock, where it meets the earth. Where there a slight crevices' that dirt could build, feel free to go heavier and higher. Use this paint to glaze horizontal areas where dirt could settle too.
8. Enhance the effect of dirt with glazes of Mournfang Brown , within the previous stages and covering a smaller area. Think about where it would be harder for wind to reach and where rain would wash the dirt for guidance.