Sylas didn't need to come across exact replicas of Ancient Serpentes to know of them. The knowledge was his so long as he willed it to be. He had never spent a particularly long time on this information because he knew that the odds he would come across one were too low.
The sheer amount of information, intricacies, and secrets these ancient lineages held went far too deep for him to consider them for long.
But… he had a general understanding of them all.
The World Serpent and the Ouroboros were two of the Legendary creatures.
It was clear that the Ouro and Boros Races were somehow related to this Ancient Serpentes, but they had veered so far from it that they no longer even registered as Serpentes to Sylas. Instead, they had become something else—the Hydra.
The World Serpent, of all the serpents, was known to have the strongest poison there was. However, even that wasn't its true ability.
