coal you mine it advance story to get materials to make the pickaxe that can mine coal
I did a couple runs of the game and sank approximately 100 hours into it. 40-50 hours of gameplay apparently yields the equivalent levels as the highest leveled character in my party is ryen at 46. I've heard of people talking about getting to level 70 and am wondering how and for what reason. I think you'd need to grind a lot to do that since my levels were mostly from completing all the quests.
before the skilltree was splitted into each character you can maximize your skilltree quite easy (maybe), so when that was that, i'm trying to complete my skilltree and end up with ryen level 94 and the rest of the team level 85, anyway here's a tip if you want to level up easly end-game : 1) you need to be in dorgania (seaside tower) 2) you need the ring of wisdom and armor of wisdom. 3) fight the elite bandit in the seaside tower, and you can get easy 5000 exp per battle with the bandit there.
(Sorry for bad english)