They didn't have to wait long to find their first enemies as they walked forward.
After walking for less than five minutes, the tunnel suddenly opened into a high cavern, with glowing stones embedded into the walls and ceiling. The light was weak, but it still lit up the cavern enough for them to see the piles of bones in the middle of the room.
There were puddles of water here and there, all of them steaming ever so slightly, and the sides of the rooms were all jagged stone, with clear nesting at their top.
There was practically no sound inside the room as they entered it, everyone watching their step to not attract attention. But it was quickly changed as a bone fell from one nest, and a harpy looked over the ledge, only to spot the intruders.
With a sudden, piercing screech, it alerted the other monsters to their presence, and combat erupted in an instant.