After the three Cerberus were killed, Alex immediately instructed others to advance towards the Abyss's main chamber. As the fighters passed the hall that were previously guarded by the 3 three-headed dogs, they could see another similar tunnel that they had seen when they first entered the Abyss Gate.
The group then noticed something that baffled them, where instead of the familiar sight of red glow covering the entire tunnel and the searing temperature, they were greeted by a rather 'normal' tunnel. They could also feel that the temperature here was rather mild, which pleased some of the fighters. If someone tried to find the 'uniqueness' of this tunnel, they could only ask where the puddles of water came from.