You get a mob spawner that you can put on your head.
Note: Minify the command to avoid issues :)
My Sunglass Head
THCommandBlocks' War Weapons
Holographic Text Command
Mob Spawner Head
go 1000mph with a walking stick
TnT
Get cool minecraft banners in ONE COMMAND NO MODS!
Herobrine's Flesh
youplops234
youplops234
lunaglimmer
dantdm
orangecreep3r
cyarith