This image presented a challenge for me, taking Stonemason's Winter Kingdom set and resurfacing it for Iray. For the terrain, I was able to adapt the snow shader he used in his more recent Winter Castle. To add snow to everything else, I had to use DA Let It Snow; which took a fair bit of fiddling with to get what I needed. I actually finished work on Part IV before I completed this part, so it will be posted right after this.