Spawn in Agathia the Friendly Creeper.
Note: Minify the command to avoid issues :)
Agatha the friendly Creeper from Stampylongnose
Fireball Nuke
Get Giant Slimes
Fried Arm
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)