Studying the Abyss
The first point of interest that came to mind in the abyss was the ground. Its metallic surface was so durable that it could withstand the battle between Nightingale and the Celestial-level Cruel Angel with only dents.
Furthermore, it was clear that it wasn't something that was naturally formed from heaven and earth; it was artificial, whether it was made by human beings or some other races.
The alloy combination made it very sturdy, but it was also very thick.
As such, it was able to withstand the impacts of the battle. That being said, it would have turned out differently if Nightingale and the Celestial-level Cruel Angel had purposely targeted the metallic ground.
After all, they were still Celestial-level beings. Only upper tier-6 and higher materials could withstand their full power.
Leon seeped his divine sense into the ground before figuring out the exact thickness and dimensions of the metal object.