Image imported from derpibooru 
Original Description:
 
Smolder loves her pony friends. Even so, she still has fantasies about destroying a city under her feet. One Nightmare Night, Celestia invited her to pull a big prank on Manehattan – which would double as an urban renewal project!
 
Reassured that everything would be okay, Smolder cut loose and embraced herself as a giant destructive monster. She took delight in the buildings crumbling between her toes, and collapsing all around her. She loved hearing the faint sounds of ponies screaming and panicking. She loved seeing skyscrapers catch fire as the electrical mains broke. Unfortunately, Spike didn’t know what was going on.
 
Even when Smolder tried to explain, Spike still felt his good friend had gone mad with power. Once he saw there were no notable injuries, he calmed down … and admitted that this was the greatest Nightmare Night prank in the history of Equestria! Spike had just one more question … could he be a giant monster, too?
 

 
Commission by Rai-Kun.