If He were to face a Troll? Maybe one day.. He planned to see the world eventually. Not sure when but Oliver had plenty of plans. Long term, he wasn't good at short term planning and there was always someone there to remind him of that.

"Well Trolls are very stupid so maybe fighting it wouldn't be the best course of action at all? You could distract it with light or sound. But i suppose if i had to fight it I might go with a few charms to protect myself instead of trying to injure the troll." You couldn't mount on offense if you'd been crushed by a club. Or at least this was Oliver's train of thought.