The Nidhog is an enormous snakelike creature that has horns, whiches direction it can control, being able to literally penetrate through the underground, no material being safe from its horns. The entire serpent is black-scaled, however, those and the usual black eyes of the Nidhog can turn green when angered or casting magic. The head of the serpent has a crown on it, made from dorns of the rosebush, which is grown to the serpent, causing it to constantly suffer pain. The tail of the Nidhog is very long, maybe even immeasurable. With the horns, the Nidhog sneaks through the ground and creates earthquakes when building up speed.
The Nidhog calling chaos into the Above in the Castle of Chaos. It is nothing but the chaos that entered our world, its poison able to corrupt almost any living being and its wrath so great even the mightiest of magicians feared the Nidhog. When the Nidhog was called into the Above, the Spaceborn indeed felt, that something was coming from "Outside" of the cosmos, but ♇ was able to convince them there is nothing to be feared from the basements of the Chaoscastle. This turned out to be a complete, blatant lie and within the depts of the castle, a Chaos Invader made its way into the Above. Knowing that if it would be discovered by Eye, ♇ hid the Nidhog under the castle and explained the dark mist by stating that the castle's aura affects the surroundings and causes Eye to not be able to look behind the walls and under the floor of the castle. So the Nidhog was hidden under the castle and the Nidhog waited there, chained to a wall of pain until ♇ turned against the Spaceborn and when this happened, the Nidhog awaited them from underground, as the underground is the Nidhogs most favorite plane. When the two lights destroyed the castle, the Nidhog was dragged out of the ground and violently thrown away. This cast the Nidhog down to Gaiga, where it made its way to the world tree.
The Nidhog made its way to the Ucuamaeya and there it dug into the ground and began to destroy the roots of it. Its poison weakened the Ucuamaeya, as it killed it faster than it could regenerate itself. But the Nidhog wasn't fast enough and the Ucuamaeya survived for a long time. It was then, that the corrupted dragon king attacked the Ucuamaeya