This actually needs two command blocks.
Note: Minify the command to avoid issues :)
The death of the enemies.
UNICORN HORN!!! ONE EASY COMMAND!!!
POTION OF NAUSEA!
NEW AND IMPROVED LITTLE PUFF!!! (Little Puff 2.0)
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)
chickendude19
chickendude19
darkknight3227
galbby5
deadpoolbadhair