Yeah, it's a bit complicated, luckily Valve released a little guide to help explain. :) http://media.steampowered.com/apps/dota2/workshop/Dota2ShaderMaskGuide.pdf
Collab with Mr.Scrake, a set for Faceless Void made by the concept from the ancient times. http://steamcommunity.com/workshop/filedetails/?id=164324318
There's lots of really good tutorials from the gnomon workshop: https://www.thegnomonworkshop.com/tutorials?tags[]=lighting-and-rendering&tags[]=mental-ray