WARNING: The following article contains spoilers for Aquaman #37, by Dan Abnett, Riccardo Federici and Stjepan Sejic, with a variant cover by Joshua Middleton, on sale now.
Magic is inseparable from Atlantis in DC Comics lore. After all, the sunken city is the home of ancient magic and its wielders, the Homo magi, an offshoot of the human species that is capable of slinging spells. So, when something happens to completely rewrite the origins of that magic, it's an understandably big deal. Such is the case with the recent Aquaman #37, which reveals the true origins of the Abyssal Dark, supposedly "the oldest magic" and "the wellspring of all Atlantean sorcery."
However, according to some very knowledgeable ghosts, that's not quite the truth.
The reveal was originally alluded to in Aquaman #34, but here the revelation is explained in full via Elder Null, one of the spectral guardians of Atlantis whose existence is bound to the very walls of the underwater city. According to Null, the history of Atlantis is something of a farce. The descendants of the city's founders have lived their entire lives believing that the Abyssal Dark is the core of Atlantean magic -- a powerful thing, yet too dangerous to be handled properly. The lie runs deep, having subsumed the truth even among the magisters of the Silent School and the Widowhood's seers.
The truth is, the Abyssal Dark had nothing to do with the founding of Atlantis. The first Atlanteans were adept at science and magic, and those crafts were instrumental in founding the city, but it was the ever-so-human hunger for more and better that led them to the Abyssal Dark, a demon that has stalked the city since its earliest days. The creature convinced the founders of Atlantis that it could be of service, as it did with the usurper Corum Rath, who has since been transformed into the demon's monstrous thrall. It sounds like the first Atlanteans quickly discovered the error of their ways and sought to right it, which resulted in a devastating war.
Since then, the Abyssal Dark has been chained by the Atlanteans, but its sinister whisperings have not gone unheard, evidenced by Rath and his transformation. The revelation completely rewrites the history of Atlantis, which is rightly considered one of the magical epicenters of the DC Universe. Aquaman #37 doesn't go any deeper into the magic war that erupted when the first Atlanteans tried to seal the demon, which leaves plenty of room for speculation.
Atlantis has a lengthy history of warfare, so it's completely possible one of the better-known conflicts was a proxy war with the demon. If that's not the case, though, and the war went down when Atlantis was still above sea level (the issue isn't crystal clear on this detail), it's completely possible that the truth about the Abyssal Dark changes more than just the history of warfare in Atlantis and might rewrite the story of the city's flooding altogether.