The main gun fired, leaving a trail of smoke for every single pony in the dream to follow as the tank shell ripped through and completely severed the Tantabus' horn from its head. The following bellow of pain was somehow even louder than the tank shot, as the lesser cloud that was once a horn fell from the tear and back into the dream as a formless blob. Even in pain, the monster still had the frame of mind to catch and reabsorb the piece with one of its pseudo-hooves.