This environment is inspired by Witcher and Skyrim and located at the peak of the mountain. The look we headed to was viking and north styled building and moody snow blizzard.
First was I did after blockout is started cut objects one by one in separate Modo files. In engine I made Master Material which you can see below. What I wanted that all material can do is ability to paint snow/dirt/gravel on them. So I used very nice technique in UE4 called material functions. The idea was simple - we need ability to paint 3 additional materials via vertex painting using RGB values (R - snow, G - dirt, B - gravel). So, instead of having a ton of nodes in main materials we encapsulate them in separate mini-materials called material functions. Each material function have own Albedo, Roughness, Normal and other outputs just like regular material do. We can bring them in our master material and just blend them using Linear Interpolation node and using vertex colors as Interpolation amount.