Nightmare Fuel / Like Father, Like Daughter

• Erebus. At first, he seems an odd Mask Man who Hekapoo oddly fears.
  • Chapter 30 on, his rampages through Mewni causes the end of all life on Mewni, save for those who manage to to evacuate to other dimensions, and the victim list explicitly includes Star and River, with the chapter ending as he gives Moon a Neck Snap.
  • He describes himself as a literal hole in the universe, and even Moon's Darkest Spell doesn't do more than temporarily injure him, and as he heals the world seems to literally shatter and rebuild itself around him as he claims that he has Complete Immortality. Not even the Lich can kill him.
  • In a Bad Future, his actions have caused massive loss of life in the multiverse. Including most of the main cast, godlike beings, and several favorite characters of other series.
  • His face beneath his mask breaks the wills of those who see it, and some people have even died from the experience.
• The Dream Eater is basically Freddy Kruger who feeds of the dreams of entire worlds. And it's fully aware of the destruction that it causes and takes sadistic glee in it.
• The Dream Eater was a horrible being that enjoyed twisting dreams into nightmares, but its demise if horrific. Basically, it's subjected to a Portal Cut variation of Death by a Thousand Cuts, numerous portals basically shredding it across dimensions. By the end, it's begging them to just hurry up and finish it off already.
• Seraph sneaks away after her nap and nearly gets eaten by a lizard. If Hekapoo hadn't found her as fast as she did Marco might never have met his daughter.
• Janna convinces Star to summon a ghost, it turns out to be a Wholly Mammoth Ghost that summons its pack that stampede through the city.
• Heinous decides to take Seraph away from Marco. Marco restrained is helpless to stop them from taking his daughter while they prepare to kill him.
  • Marco, once he gets free, is more than willing to kill Heinous. The only thing that stopped him was that he didn't want Seraph to see something like that.
• In order to get around how space itself prevents Erebus from being permanently damaged, Hekapoo evacuates and collapses her dimension, nearly killing herself if Marco hadn't saved her.
• In a flashback, we see that Erebus once used a ritual to kill an entire planet's worth of beings, their deaths fueling the creation of a Genius Loci spirit bound to his will. After Glossaryk defeated him, Glossaryk destroyed the entirety of what was left of the planet, proving just how dangerous he is under his silly behavior.
• The Toffee-possessed Ludo fled to Earth to escape Erebus, and he opens up a portal on a cave painting of Bill, Toffee offering an entity inside a deal...
• Something is messing with Marco and Seraph's dreams...
• Toffee, to spite Moon even more, arranges for Gravity Falls and the kingdom of Mewni to collide.
• The Collective is rather terrifying. A technological Hive Mind of a Straw Vulcan race sealed away long ago for experimenting on magical being and disrupting the balance of magic, when some of them escape to Earth via the recent disruptions they start subjecting people to Unwilling Roboticisation for eventual Brain Uploading, genuinely not comprehending the idea that some humans might not want to give up their bodies to become immortal beings of data like them.

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