A pigzombie boss!
Note: Minify the command to avoid issues :)
Go to all the different gamemodes in one sign
Simple Zombie Boss
MOST OVERPOWERED GOD POTION
Emeralds and Diamonds Trader
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)