Arrows of harming

Abandoned mine shafts are tunnels added in the Adventure Update, 1.8. In 1.8, these Shafts appear to be abandoned by probably previous Minecrafters in the tunnels(not really, but that's the story). These tunnels can often be littered with Torches on Walls, Wooden Supports, and Webs all around. You can typically find a Spider Spawner nearby, if you find a Shaft.