Setup

Spider Swarm (S) (MV pg 301)
2 Dark Creepers (D) (MM pg 49)
2 Shadowhunter Bats (B) (MM pg 27)

The party drops or climbs down into the easternmost area, just north of the pool’s edge. When they arrives, all enemy combatants are hidden. All have total cover, meaning it is not possible to see them. Hearing them will be difficult. (Perception DC: 25 for Dark Creepers, 21 for Shadowhunter Bats, and 21 for the Spider Swarm.)

You’ve entered a large dark cavern, eerily lit in sections by the yellow glow of strange crystals. There are two exits from this room, both cliffs, one of which appears to have an old rope and wood bridge attached. Just next to you, there is a pool of water of clear water.

Tactics

The Spider Swarm waits until someone is crossing the chasm (likely by the bridge) before scrambling up from the cavern floor to attack. Alternately, if someone should climb down or fall in, it will also move to attack as soon as possible.

The Shadowhunter Bats are impatient, and will attack after a few minutes if the group hasn’t already attempted to cross and been engaged by the swarm.

The Dark Creepers are patient, waiting until someone has reached their side of the chasm, at which point they will try to cut them off from assistance by cutting the bridge (or any other ropes, etc used to cross). When they attack:

A pair of small gnome-like creatures rush forward brandishing unusual-looking single-edged daggers. They snarl and drool, fading in and out of darkness and they slip quietly toward you.

Features of the Area

Chasm: The chasm in the center is 50’ deep in all parts. Its walls are uneven (DC 15 Athletics to climb).

Crystals: Two clusters of Doomlight Crystals (DMG2 pg 59) each shed dim light in a 3 square radius.

Rope Bridge: The bridge is badly rotted and precariously tied. It requires a DC 20 acrobatics check to maintain balance while crossing (at half speed).

The Southeast Pool: The pool is only 5 feet deep.

Perception (DC20):

The water is mostly clear, but you notice traces of residuum in it.

If the party takes the time and finds a way to sift it out, they can collect 1gp worth per person sifting per minute, to a maximum of 150gp. Using the Lower Water ritual can trivialize this process.

Cache beneath bridge: In the pile of rocks beneath the middle of the bridge can be found 3 Gravespawn Potions (AV pg 187).

The Dark Creepers’ Daggers: the Dark Creepers each carry 4 normal daggers, for throwing, but fight in melee with strange single-edged blades. The two blades are an identical pair, and each has a small hole in the base of the blade. Together, they form The Shears.

Smaller, Northern Pool: The smaller pool is only 2 feet deep. It contains nothing notable.

Crack in the West Wall: A narrow break in the wall in the west leads into The Spiderhole.