Minecraft wiki entry for Block_and_item_duplication, associated text: Extra info: these files also contain your current location and your exp. Theoretically, you can enchant some gear, deposit it in a chest, then load the level.dat file to preserve your level and keep the enchanted gear. Another potential use is to use up your inventory while building then load a backup to keep your progress and refill your inventory with the building material. You could even use this to try multiple times to kill the Ender Dragon / Wither without risking your gear and inventory.