Also here's an image showing the shiny/reflective material of the bomb using the Brazil Advanced Material.
Lighting and Rendering
My goal for lighting and rendering was to create a painterly image with depth and atmosphere in a sfumato flavor. I began lighting by using my concept piece as reference. First, I had to place the direct light source. In this case, the sun is the direct light source, but most of the illumination from the scene is going to be caused by the sun's light bouncing off the sand/rock resulting in soft diffuse shadows. My solution for tackling this was using area lights, faking the bounce.
Before lighting I decided that for the final composition I was going to use a primary beauty pass along with other passes including diffuse, z-depth, light rays, ambient occlusion, vegetation, and several custom masks to isolate and color correct sections such as the bomb in Photoshop. Also, by saving my renders off in a floating point format such as openEXR I would be able to re-expose and pull details that might get blown out or too dark. By using passes and floating point images, I can spend less time re-rendering and more time tweaking my image in Photoshop.
Below is a screen grab of the viewport with the lights in place followed by a top view of the scene with a summary of all the lights used and their core settings.