I WANT IT SO THAT WHEN HE HAS AROUND LESS THAN HALF HIS HEALTH GONE HE WILL START TO STOMP AND MAKE BLOCKS FALL FROM ABOVE, I REALLY DONT KNOW HOW TO MAKE SPAWNERS SEND THESE TYPES OF MESSAGES OR MESSAGES IN GENERAL! PLEASE HELP! 
LINK TO THE GAME: https://flowlab.io/game/view/1188378
NOTHING IS DONE TO THE GAME SO FAR JUST BECAUSE I WANT TO MAKE SURE THAT I KNOW WHAT IM DOING BEFORE I JUMP INTO THE MAKING.