When June raised that finger gun in Charles's direction, Negomalrog knew that the actor was going to kill. After all, he wouldn't be marching here if he was not after some results. He just didn't realize that June wouldn't give Charles time to beg or curse. As soon as the upper body went, it was the start of a battle June might or might not survive.
It's just that before the grand demon could even morph to instill fear in the human, a loud explosion came from the remaining part of Charles's body. It was as if June deliberately made it go off like a bomb. Negomalrog used his magic to shield his eyes from the blindness caused by the flames and the spark of the explosion. However, the detonation actually wrecked the whole office apart.
