Easy it's just a Ghast Riding a GIANT
Note: Minify the command to avoid issues :)
Diginer's Axe
Annoying Villager Murderer
Troll Potion (Troll ur m8s)
Notch Book Troll
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)