"Hahaha!!!!! No problem. This is actually a good thing. For years my brother and I have been worried if I day might come when the uncountable number of zombies from The Obsidian Throne Ruins will find a way to get out. Fortunately, now all the zombies are dead."
Whenever Sebastian and his brother tried to explore the labyrinth, because of the darkness and the huge number of zombies, they were always unsuccessful. It took the Ashford family nearly one century to map just 21% of the entire Labyrinth.
The reason for this was simple. Whenever any group of Ascenders entered the labyrinth, a massive number of zombies would attack them. And the worst thing was, that fighting such a massive number of zombies in such a narrow space was really difficult. And the people and Ascenders who died inside the Labyrinth were also turned into zombies.