Since I discovered this awhile ago so after rewatching the game’s cutscenes I decided to propose this creature IH since I like touching characters that no one else will lol.
What's the work?
Seven Deadly Sins: Grand Cross is a mobile game based on the Seven Deadly Sins Manga/Anime series. With original stories and characters of the Seven Catastrophes and Rangarok: Fate of the Gods.
Who is it?
Nidhoggr is a antagonist in the Seven Deadly Sins: Grand Cross Rangarok Fate of the Gods storyline where it is one of the many Demonic Beasts that serve as one of the story mode bosses and Demonic Beast Boss Battles.
What Makes It Heinous?
Heinous Standards
I do know comparing Nidhoggr to the Demon King, Supreme Deity and Cath would be unfair if the story is canon as while it is an demonic beast it isn't some godly being just a powerful monster, same reasons for the serie depiction of the Norse gods so comparing Nidhoggr to Odin and Vali even while weakened still be unfair while Tyr and Freyja fails the heinous standard as well since Tyr attempted kill count isn't enough while Freyja suffers from too much fridge-horror since her killing many fairies happened offscreen.
Even when factoring the Ten Commandments and Lillia it would still stand out due to it lacking anything similar to the Commandments.
Heinous Acts
It was stated it attacked the underworld previous times and had to need Hel and Baldr drive it away in the past before the events of the storyline.
In present day it would attack again this time eating the world tree root supporting the underworld and was aware of the inhabitants in there as it was causing damage to it, where it would’ve destroyed the underworld of the Seven Deadly Sins and their allies they made didn’t drive it away as the underworld’s destruction would’ve plunged every single living there and any new being that would’ve in a fate worse than death since souls would have no where to go become wondering souls.
Although even if storyline is canon to main series even when factoring in Melascula it would out heinous her since it had a higher attempted number since it would’ve plunged everyone in the Hel’s underworld kingdom in a fate worse than death plus Nidhoggr don’t have anything close to the Commandments for resources as it is a large powerful dragon not a god like being and has much screentime than her.
Possible Preventing Factors?
Although it may look like it rely on fridge-horror on paper, a few lines prevent it from being the case as it was outright stated stated by Hel herself being a wondering soul is a lot of suffering and painful which is considered a fate worse than death since anyone who died before she and Loku founded the Underworld being sole reason it was made so souls can rest. So Nidhoggr destroying the Underworld would’ve plunged all of those souls inside of it in a fate worse than death had it succeeded.
Here are some screenshots to back up my claims.
Although it was stated to be Evil in personality nothing suggests it is made of evil at all.
What Makes It Inconsistent?
While it shows an moral agency due to it reacting to the Sins and co attacking it plus described to have an evil personality but it mostly acts as a destructive monster so it makes Nidhoggr an "Generic Doomsday Villain" so it can't be PE or NPE.
Verdict
I say yes since destroying the Underworld would’ve plunged the souls of those who died as wondering souls and do not rely on fridge-horror at all since Hel and others stated it was considered a lot of suffering and a Fate Worse Than Death and even when factoring the main series villains it would still stand out from them since none of them tried to destroy an afterlife and plunge everyone in it in a Fate Worse than Death.
However while it shows agency and intelligence, it acts like a destructive monster making it an Generic Doomsday Villain.