At first Maul isn't sure what's going on. Then as the pain starts he realizes that this opponent has done something to his mouth. There is a muted sound, a growl of pain or rage or both that cannot escape Maul's mouth for the simple reason he cannot open it. His mouth is fused shut by whatever strange magic this man has at his disposal. It's creepy, weird, and painful, but there's nothing in it which sets off the fear or panic that so often rise when Maul encounters something that reminds him of his past.

No, all he feels right now is just usual rage of wanting to defeat the opponent right in front of him. He leans forward and headbutts the Emperor hard, jutting his head downwards and then back up. No one in the galaxy ever wins when it comes to getting headbutted by a Zabrak. They have horns for a reason.

Well, if this man can mess with his very bones and seal up his mouth as if he is nothing more than a doll to be played, Maul decides to see how well he he was able to do so without oxygen. His hand doesn't come up the way most Force users do to emphasize their actions but still the Emperor will feel his windpipe slowly be closed as surely as if two hands are wrapped around his neck trying to choke the life out of him.