Annoying boss monster

"What kind of monster do you think it will be?" Claudia asked while leisurely trodding behind the man.

"A goblin?" Tom replied with a question on his own. "Maybe a slime?" he continued guessing for a while before shaking his head. "If it works just like in-game, then we can guess for an entire day, and we still might miss," he said.

Each of the dungeon's floors had a limited number of different monsters populating it. It was a truth that Tom learned even before discovering how the entire Dungeons Online was just a ruse to cover an actual dungeon that he was in right now. But while he couldn't understand why the game developers didn't share any information about the rules within the dungeon before, it turned out to be quite simple now. 

The owners of the game never shared any details of it with the players because they never were behind the creation of the dungeon in the first place.