Unlike the version in the mythology, Nidhogg actually went mad in the process of gnawing the root of Yggdrasil. After that, the black dragon turned into a monster that only knew destruction and killing. What it bit was one of the First Born's nerves, not anywhere else.
Its lair was located just above the nodes of part of the brain tissue of the First Born. This unfortunate fellow. It chose to build its lair on a super powerful mental energy transmitter, which doomed it from the very beginning to a painful end. Even if Nidhogg did not touch the vines and blood that spread from the underground, it would sooner or later become mad in dreams by listening to the whispers of the First Born.
Hao Ren left Anthony, Y'zaks, and Y'lisabet on the ground to stand by, and then led others into the vast cavern beneath Nidhogg's body.
