I picked Ogre Magi so that I could compare to Valve's render in the shader mask guide[pdf]. Haven't been able to use all the 8 different grayscale masks, but there's more work to be done here.
Colour and normal maps were the easy part but then came the specular intensity and specular exponent masks. Using general techniques would achieve results like these. Too much glossy there. After much experimenting, here's the starter node setup for the materials that I finally used. A node group was created and used for each object and just the image textures changed.
One thing I feel I got right is the self illumination mask setup. Magi's weapon in this render corresponds closely to the one in Valve's shader guide.
Stuff I couldn't manage:
Transparency on the cape. I couldn't find any clues in the shader guide as to which mask corresponds to transparency. It could be the Fresnel mask but I still have to figure it out.
Specular highlights are not as prominent when compared to the render in the shader guide, but this I feel looks a bit more realistic.
Rim highlights. Absolutely no idea how to get that in blender. Maybe with appropriate lighting specific specular maps. These highlights are more specific to the game and may not be necessary in a model render.
Detail map mask. This might be easy and could be tried with Razor.
If you have any suggestions, improvements that could make the render better, or you need the source blend, please let me know.