Nidhoggmon is a colossal Digimon that is constantly taking in a tremendous amount of energy, leaving it in a perpetual state of thermal runaway. The light emanating from its wings is a sign of what stage of thermal runaway it’s currently in, as that light turns redder and redder the closer Nidhoggmon gets to the danger zone. Locked into a constant cycle of energy absorption and destruction, after Nidhoggmon passes through an area, it leaves nothing in its wake.
Its special moves include Annihilention, where it fires red-hot beams from its eyes, and Rudiment, which involves condensing the energy inside its body into a wave that it fires from its mouth.