Nidhogg will survive Ragnarok and feast on all the wicked dead in its aftermath.
Nidhogg is fated to finally eat through the entire root at Ragnarok, causing Yggdrasil to collapse. Nidhogg is located by Hvergelmir ("roaring kettle" source of all cold rivers), one of the three wells/wellsprings located around Yggdrasil, in Nastrond ("dead body hall"), located in the world of Helheim or Niflheim, where it feeds off of corpses to sustain itself. In Norse mythology, Nidhogg was a dragon who gnawed on one of the three giant roots of Yggdrasil, the world tree (a giant Ash tree which connected all 9 worlds of Norse cosmogony). Nidhogg will Rage after 60 minutes of being engaged.Nidhogg is extremly resilient to Sleep, therefore Elemental Seal is usually required, beware as Nidhogg quickly builds resistance to Sleep.