They had to fill in a mana stone to get past the entrance of the third cavern. Bog hadn't lied. There was indeed a swamp past that way. Jean placed another barrier stone at the entrance. So that both Atha and Bog could be safe.
As soon as they took a step inside the swamp, they saw something glow in the dark. It looked like a lantern's hook. Then, a big fish rose from the water.
"That up there is the dungeon core," Morris pointed at the glowing crystal. "It must have merged with the boss mob."
"Well, it is going to provide light, then. All the better for us to fight it," Jean joked. In reality, their situation was grave. A boss mob-dungeon core mix benefited from all the mana of the dungeon core and all the sturdiness of the boss mob. They were going to be in for a big fight.