The black dragons-
One of the strongest dragons- originating from the underworld.
Most of the dragons of our world came from the moon- and lived on the moon. But not the black dragons. Long ago- they too lived on the moon but due to their 'evil nature' or something like that- they were kicked out and found themselves in the underworld. Having deep hatred for the upper worlds- they sought vengeance and one of their strongest- Actagorn somehow ended up freed during the great Torban wars-
And that dragon destroyed the seven great nations- tainting the world in red-
Of course, the dragon empress stopped the dragon before it was too late and somehow mortally wounded the black dragon…
Known as the destroyer of worlds-
One of the nine plagues-
You should keep in mind that the dragon is more than at least 10k+ years. And they usually live for 12K years-
So he's literally at the very end of his lifespan.
He's definitely the toughest enemy so far in the entire novel though- at least in the main storyline.