Trolls and their Enchanted Loot

A monster that, instead of burning in daylight, turns to stone until nightfalls again. While made of stone you could mine it to give you cobblestone. It would drop a map to a troll cave, (like treasure maps), where you would find either enchanted books or just plain enchanted gear.

In combat, it would act like an Iron Golem. You could find one in dark oak forests or taiga forests.