Nightmare Fuel / Enter the Arena as Your Avatar

• Starting here, Hazama shows his true colors. Beware of major Deemo spoilers. The Girl's behavior afterwards makes it even worse...
  The Girl: "I want to remember this taste so that way, when I rip his flesh from his bone... I can smile in glee..."
• Spiralblock Peak introduces The Flood to the Arena, in all its squicky glory. Nightmare Retardant is in effect, as it can't infect avatars because it would be cheap if it could. Becomes a Moment of Awesome when Kirby and Darius combine powers to kill the Gravemind.
• A several-months-long plot initiated by KiriK happens in the spinoff Arena. The plot is a direct adaptation of World of Light, and what does that mean? Everyone dies at the beginning.^note Slightly mitigated because unlike in Smash, there's a lot more than one survivor, but DevilPsyco still threw all but four or five characters of his entire roster to the metaphorical lions.
• Dokan, the cute Flareon, is besieged by demonic sheep. Despite the mild comedy in that premise, the sheep are nightmarish in their assault and ultimately leave him exhausted and broken before tearing him to shreds.
• Here, two kids from Five Nights at Freddy's get into a fight - Charlotte Emily, formerly the ghost possessing the Marionette/Lefty until she was revived, and Andrew Afton, the ghost possessing Golden Freddy. Andrew hates Charlie for getting her life back despite the other animatronics being stuck in their states, and so in their fight in which Charlie is just trying to calm Andrew down, he keeps trying to brutally kill her, and when she finally gets him to submit, it's only by an Emergency Transformation into Nightmarionne, which would've destroyed Andrew's soul had the overpowered Erma not stepped in. Though the fight was between traumatized kids and the scale was extremely low, the stakes were as high as they could possibly be.
• While BE!Overclock's attack on the SIs ended up awesome for the monstrosity's defeat, there was much terror and uncertainty along the way.
  • It Tele-Frags Rhea, the team's de facto mission control...
  • Dices an Arceus, Bahamut, and Geo to pieces...
  • Shrieks so loudly it reduces Ami to paste...
  • Cuts off Erma's arm...
  • And is generally just absolutely nightmarish in behavior and demeanor. Even when finally slain, it nearly self-destructs to take out the SIs once and for all, and only a Deus ex Machina saves them from mass obliteration.
• As part of his training by the Swordmaster Dragon Lord Altzaira, Zenitsu is dropped into the depths beneath the Dwarven ruin of Kagrenzel and unwittingly awakens something immense and vile lurking in the dark, eventually revealed to be Syvyys Scuru Atramentis, also known as the Deep Darkness Dragon Lord. What follows is a spine-chilling chase that transitions into a moment of awesome as Zenitsu finally gathers the courage to fight back against his tormentor. Starts here.
• Arachnos' "Mindwalker" Omori is a Tulpa that detached from its progenitor and now clings to anyone with intense regrets, manifesting their trauma and tragedy upon their soul to try and drive them to suicide. There's a lot of potential victims in the Arena.
  • He succeeds against Taranza here.
  • He very nearly pulls it off on Chara in a scene starting here, only fails due to the intervention of Madotsuki who overwrites Chara's headspace with her own to save the child, and could've worn Madotsuki down too, only failing at that because she wakes herself up to forcibly escape the encounter.
  • And then, he meets Vanitas here, and the two beings born of and fed by emotional darkness and suffering team up, with Omori now able to manifest in the physical world in a similar fashion to Ansem's Dark Figure, and Vanitas able to use Omori's abilities to read and weaponize the trauma of others. Woobies, anti-heroes, redeemed villains, and all sorts of others had better beware.
• The number of fully-fledged characters in the Arena who would realistically lose a fight to a Five Nights at Freddy's animatronic (those with Adaptational Badass superpowers notwithstanding) can probably be counted on two hands. One of those characters, a policewoman named Janine, has the misfortune of running into one of the most dangerous, cunning, and cruel animatronics there is: The Mimic. Arriving in the Pizzaplex to investigate the fates of a group of nosy teenagers, she soon finds out exactly what happened to them... and joins them. No sooner has she respawned from her grisly demise than does Fomortiis show up to give a... very enthusiastic rant about how much better torture is than simple murder. One that seems to have struck a chord with the Mimic, as well as another third party intent on making use of its talents...