When the Nightmare Knight comes face to face with Cucumber and Nautilus, a bit of verbal back and forth ensues and results in Nautilus declaring that, if they work together, they will have the power to defeat him for good. The Nightmare Knight responds to this by pulling out a miniature sun and holding it like it's just one of his weaker attacks.
Nightmare Knight: Amusing. In that case, show me this 'power' of yours.
Noisemaster. Not only is the man Obfuscating Stupidity around the Nightmare Night, but he takes the opportunity to trick Almond into triggering Mutemaster into action and get Princess Piano to give his Noiseblaster a full charge after having her witness Nautilus (almost) get killed. When he says that he doesn't want to play around anymore, he means it.