Minecraft wiki entry for Loot_table, associated text: Loot tables are namespaced. To create a custom loot table, first create a new folder for the custom namespace, and then create loot tables within following a similar structure. Then, summon the mob with the data tag DeathLootTable set to the name of the directory and file (without the .json extension), such as DeathLootTable:"custom_namespace:path/to/table".