Spoilers Off applies to all Nightmare Fuel pages, so all spoilers are unmarked. You Have Been Warned!
A slow painful end. For Kids!
- In "Deja Foo", Yang has to watch Ultimoose burn Yin and Master Yo to death until they're ashes. They don't show much, but it's still a bit unnerving.
- Brother Herman, albeit a comical Large Ham, is still a blatantly murderous warlord, who often makes threats of trying to tear off the limbs of enemies. At one point, he threatened to rip off his brother's legs and even planned on cutting off Yin and Yang's feet.
- Though comical, Saranoia's blatant mental illness is not Played for Laughs in-verse and she becomes blatantly creepier with each appearance due to her obsession over Yin and her desire to murder Yang because of her own childhood trauma involving her abusive father and favored brother. The fact she keeps calling Yang her brother's name and Master Yo her "daddy" makes it even worse.
- Yuck's flashback in "Upstanding Yuck" explaining how he became good is framed as comedic but has a lot of dark undertones. Yuck, getting what he rightfully deserved for mindlessly terrorizing a town, is abducted and given a No-Holds-Barred Beatdown what could have possibly been days. Paired with the Art-Style Dissonance of a children's drawing, it just opens up the possibility that this child, no matter how evil he may be, was being repeatedly beaten until he was mentally conditioned to goodness. And it worked, but at what cost?
- Yang's situation in "Disapp-Eared" is absolutely terrifying when you think about it. Due to completely misfiring an invisibility spell, he's rendered intangible and inaudible, basically reducing him to a walking ghost that no one can acknowledge. He's clearly able to reverse the effects but if he hadn't learned a way to communicate through sonic farts, he could have been like that forever for no way for anyone to know what happened to him.
- Some of Yuck's twisted-looking Nightmare Faces (especially in "Yin Yang Yuck!") can get pretty creepy. Even worse is how Yuck's possibly the most powerful Woo Foo knight in existence, nearly killing Master Yo the first time in a mostly one-sided fight and having all the power of Yin and Yang combined. The only reason they survive him at all is through some Deus ex Machina.
- The fact that the Nightmaster was able to commit mass genocide against every Woo Foo practitioner except for Yo and possibly wouldn't refrain from doing it again by finishing off the titular trio.
- The Box of Infinite Trapitude is an artifact introduced in "Mind Games" used to trap the psychic Ella Mental. Even the name alone implies what a horrifying fate it would be, essentially a locked box that seals anything inside it forever with only yourself and your thoughts to keep you company, possibly forever.
- The Woo Foo Aura Drain is this, especially considering that a Woo Foo-powered being losing their abilities is enough to kill them unless they find their parent or child for an aura transfer: when Yin is hit with one of these by Eradicus, her eyes become entirely black and her body is frozen while her abilities are drained out of her, leaving her weak and dying. What makes all this even worse is that neither Yin, Yang, or even Master Yo knew they were related. Yin and Yang grew up as orphans thinking that Master Yo was just their mentor and not their father and Master Yo did not know that Yin and Yang were his kids, as his memory was wiped when the duo were born. If it was not for that lucky accident, Yin would have died.
