Cow.
Note: Minify the command to avoid issues :)
Silver Sword (In CMD Block)
Mr. Pusher LVL
Champion Attacker's Helmet (1 Hit Kill Everything)
Mr. Pusher LVL LVL LVL LVL LVL LVL LVL LVL
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)