Demon Spider.

Spindle came back to report quickly, the dungeon gate was erected in the middle of a large cavern.

It was surrounded by monsters, giant ants, worms, slimes, and even some cave alligators. There was no sign of the boss monster's location, that thing might be hiding somewhere or he is just blending in well. It wasn't uncommon for boss monsters to be a rare type of a weaker monster, A king slime for example looks exactly like a normal slime when not irritated.

"Wait until I make my move," Cain said as he disappeared with [Invisibility] The girls had to wait and see what will he do.

Cain climbed the wall and watched over the monsters, slowly preparing his magic. The cavern was big but he should be able to cover it with multiple [Fireball]s. He started concentrating on his magic, gathering a massive amount of Mana in his hands.