The Kuo Toa captured a drow scouting party led by Derinnil d’Noquar. She is the only one remaining and is being prepared for ritual disembowelment.
The ziggurat of the kuo toa hides a monolith beneath tied to the Elemental Plane of Water and one of the ancient monoliths of the Black Cathedral.
Priest-Prince Va-Guulgh leads the kuo toa of their ziggurat. He is vain and bloodthirsty. He believes he is a chosen child of Blibdoolploop.
Va-Gullgh is served by his Master of Assassins – Quolp-Ool.
Blibdoolpoolp – patron goddess of the kuo-toa, a paranoid, reality-denying deity of the sea of questionable sanity.
Filled with pain for the suffering of the Kuo Toa.
The Drowning Goddess resides in the Murky Depths or the Fated Depths inside the Elemental Plane of Water.
She wears a string of pearls with various powers. Va-Guulgh hopes to give her the Heartstone of the Serfneblin to add to her necklace.
A continual cold war exists in Erelhei-Cinlu. House Eilservs rules the other houses of the city, but is constantly threatened by the other houses. Matron mother Eclavdra dEilservs is the matron mother of Erelhei-Cinlu.
Several gods and demon princes seek to use the Black Cathedral as their conduit to Oerth – Orcus, Demogorgon, Lolth, Blibdoolpoolp the Sea Mother. The Black Cathedral is the battleground of their followers.
Each destroyed obelisk tips the balance of chaos surrounding the Black Cathedral. Only the souls of the dead can solidify it and crack open its massive doors.

Fantastic Locations

Altar of Blibdoolploop – Huge crustation statues, blibdoolploop statue, elemental water pool
Throne room of Va-Guulgh – Throne of bones, blibdoolploop statues, secret door
Chamber of the monolith – Elemental pool, monolith of impossible angles

Notable NPCs

Thoopshib the Kuo Toa Bargemaster – Likes gemstones
Quolp-Ool – Master of Assassins
Derinnil d’Noquar — captured drow scout
Priest-Prince Va-Guulgh — Kuo Toa leader

Monsters

Kuo Toans CR 1/2 AC/DC 12 HP 22 Atk/Prof +4 DPR 8 Atks 2 × 1d6 + 1
Kuo Toa Monitors CR 3 AC/DC 13 HP 65 Atk/Prof +5 DPR 23 Atks 2 × 1d6 + 9
Kuo Toa Assassin Priests CR 6 AC/DC 15 HP 112 Atk/Prof +7 DPR 41 Atks 3 × 1d6 + 11
Giant Crabs CR 6 AC/DC 15 HP 112 Atk/Prof +7 DPR 41 Atks 2 × 1d6 + 18 – restraining claws.
Avatar of Blibdoolploop CR 12 AC/DC 17 HP 175 Atk/Prof +9 DPR 77 Atks 4 × 1d6 + 16 – maddening gaze – gripping claws.

Treasure

114 SP, 2346 GP, 119 PP
3 × 100 GP garnet gemstones
200 GP shadowy gemmed gold crown
Nightmarish spiked lamp that casts Magic Jar once
Ioun stone of agility, awareness, leadership, protection
- Chime of Opening
- +2 ethereal mace

Summary

We hear a drow yelling for help. We see an ornate door with embedded shells and engravings and an 5-pointed star indentation that is a key hole. Chartreuse is pushed to her limits as she picks the lock. She sees an imprisoned female drow, who is being guarded by giant constructs - kou toan flesh guardians. We fight and kill them and free the drow who is Derenil, the drow we were asked to rescue. We give her a rapier and let her head home after she gives us the lay of the land, including the location of the monolith -- either via a pool in the throne room or beneath the ziggurat. We head toward the throne room, as we hear the guttaral noises of many kou toans.

We head toward the throne room, seeing all the kou toans praying to the statue of their god with the monitors keeping them in order by killing them when they approach. We see a priest kill an imprisoned drow. In walks Va-Guulgh (with gemstone) and Quolp-Ool and two more monitors who we fight. As we fight, a weird green glow emanates from the top of the ziggurat. As we fight the prince and the assassin and their monitors, the rest of the bad guys run into some trouble with gravity and smash against the ceiling and the ground to messy effect. After we kill everyone except the prince (who ran inside), the statue at the top of ziggurat crumbles and out comes an alien horror. We down some healing potions and rush into the throne room...