((In the interest of moving things along, I'll assume you search the chamber.))
You find nothing in particular of interest in this chamber. As you continue around the corner, the echoing sound of running water fades behind you. The chamber ahead is of similar make, but has a large crack running through the center. Luckily, it's easily traversed.
At roughly the same time, Boon, Willow, Isaac, and Snowy all notice something odd about a couple of the stalactites hanging from the ceiling above you. Before you can react, 3 of them loosen their grip on the ceiling and let out piercing shrieks, before the room plunges into blackness.
((Initiative, please. The Boon, Willow, Isaac, and Snowy get to act in the surprise round, and know the spaces where the creatures are. If/when the darkness goes away, I'll post a battle map.
The ceiling is low enough to attack for anyone who is not Small.))