Welcome to Librarium Online!
I'm starting to paint a stone troll with two-handed axe.
I need some advices on which colours are more suited.
I don't do O&G but all the Stone trolls I've seen are Blue. Have a look in the army book, but I would say Regal Blue with a Blue in wash to go between the cracks. And highlight with either Enchanted Blue or Regal Blue mixed with Skull White.