This is my outpost where I currently mine from. I got the hellstone in the underworld of a friends (Chaotic's) server. I'm not hurt because of the Obsidian Skull's nullifying effect for Hellstone. Since it is just an outpost, no NPCs can be hurt. There are also lava pits to the side for enemies that walk. I need to make a third hellpit on the uppermost exit though, just to make it match the other two (few non-flying enemies can get up there safely after all).