The Nightmare dragons are a race of Evil Dragons that live in the True Immortal Realm, and they not inferior to the Ancestral Dragon. Since they're the patriarch to devilish dragons, they are the sworn enemy to True Dragons. Their blood give off the aura of a True Dragon, however when not refined by true dragons over time, it will contaminate one's magic power, and turn them into a projection clone of the Nightmare Dragon. When refined by a True Dragon, it will only retain 10% of it's power, and can only be used to enhance one's magic power. This is mainly used to help True Dragon's below the Grand Ascension stage to break through into True Spirits.