I used MrGarretto's command combiner, so this is not entirely mine.
Note: Minify the command to avoid issues :)
It's a surprise...
Too much Pym Particles...
Batman Geared Leggings
Boss Battles! Now not impossible!
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)