prime Black so we get better contrast in the cracks
Sponge on Dragon Fang or any mid brown like like Zandri Dust . You can go back afterwards with a brush to make the coverage more consistent if you want, just avoid the cracks
Sponge on Vampire Fang
Sponge on Pale Sand
Roads: sponge on Incubi Darkness or Dark Reaper
Highlight roads by sponging on Wolf Grey or any other desaturated bluegrey, like Russ Grey
Pick out metal areas using Sir Coates Silver or Dragon's Gold . Use a wash if you want, or just use an oil wash later.