This actually needs two command blocks.
Achtung: Minifiziere den Command um Probleme zu vermeiden :)
Your Custom /tellraw! (1.8)
Dogman
POTION OF NAUSEA!
walcom hom jimmy
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)