Nidhogg, the Norse world-serpent/dragon, embodies decay and destruction, featuring abilities like soul-destroying breath, existence erasure, powerful physical attacks (claws, tail), and often toxic/corrosive gas or fire breath, alongside extreme regeneration and immense strength, allowing it to consume corpses and gnaw World Tree roots, with variations in games adding ash manipulation, miasma generation, and anti-magic scales.
Core Mythological Abilities (Norse Mythology):
Corpse Devouring: Nidhogg constantly gnaws at the roots of Yggdrasil, feeding on the bodies of oath-breakers and murderers.
Destruction: Its primary role is as a destroyer, embodying malice and chaos.
So Loki could have soul destroying hax alongside extreme regeneration. Especially the latter makes sense since Loki cannot possibly start the battle against Imu with all the injuries. He has to recover from his wounds somehow.