Nether Dragons are always implied to be special and different from normal dragons, but we never see it. What special abilities do nether dragons have exactly that normal dragons do not?
They can shift between Astral and Physical Planes and are immune to Arcane and Shadow Magic…
Infusing their essences into Dragon Eggs results in Twilight Dragons which are Void Dragons that can shift between Astral and Physical Planes.
Twilight Dragons can also be created from straight Void infusion so the Nether Dragons’ only unique nature is being a hybrid between Twilight Dragon and Arcane Dragon.
Deathwing’s Clutch holding Void corruption is expected since the Void corrupted the entire Black Dragonflight so all the Twisting Nether’s energies did is add Arcane energies into the mix creating Arcane Dragons with the ability to shift planes due to the Void corruption they originally had…