Minecraft wiki entry for Multiplayer_PvP_bases, associated text: This step is optional but recommended. It's a good idea to have a secret door that leads to a basement located at an even lower depth than your main base. There you can keep a secret storage room to stash your valuable resources in (be sure to leave some of your iron/gold/diamonds in the main base. If enemies break into your base and find no resources, they'll probably figure out there's a secret room), and also a library to store books containing information on enemies and their bases.