d
Note: Minify the command to avoid issues :)
More pickaxes in one command
Armored Dragon (impossible boss battle)
Hostile Archer (1.9.1)
More mobs in 1 command (Read The comments!)
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)