Note: Minify the command to avoid issues :)
ITEM SPAWNER!!! (WORKS) 1.12
ITEM SPAWNER!!! (WORKS) 1.13
ITEM SPAWNER!!! 1.10
ITEM SPAWNER!!! 1.8
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)