This will spawn a normal iron golem, but when it fights mobs...
Note: Minify the command to avoid issues :)
Super Annoyingness!
OP Traders!
Creepus Explodus
Paulyak Hoe
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)