After taking a long rest to recover from their street fights, the group heads into the warehouse:
In the areas where the walls and ceiling didn’t collapse, this warehouse contains no crates, no boxes, no barrels, and no wares of any other kind. Directly in front of the missing door, the walls, ceiling, and floor have fallen away to reveal a deep sinkhole fissure. Inside the ruin, a hempen rope anchored firmly in the rubble dangles down into the darkness. The tear in the earth descends at an angle, making it impossible to see how far down it goes or what waits at the bottom.
Eric the Cleric (“Grrn”), cast light on a rock and tossed it down the opening. Nothing moved, nothing could be seen, so the group descended using the existing rope to get to the bottom.
The sinkhole fissure ends at a level floor of worked stone. Dust, debris, rocks, and pieces of wood that once made up the walls and ceiling of the warehouse above are spread across the floor. An underground passage is blocked to the south, but it continues into darkness to the north. Two pairs of human-sized boot prints, easily spotted in the dust, head northward. Smaller fissures, holes, and cracks riddle the passage, though even a halfling would find the largest of them a tight fit.
The group begins to explore for a bit when they are attacked by 3 large rats. After a round 3 more join in the fray. As the last rat dies, it coughs up a humanoid finger bearing a platinum ring worth 20 gp. Etched inside the ring is the name “Burton Boot”. On closer inspection the adventurers notice the rats seem to be dyed green.
The earthquake sealed many of the passages that once made up this underground maze. As the characters explore, they pass through worked tunnels, natural caverns, and functional sewers at different points. Most side passages are blocked by rubble, making the path of the two Waterdeep City Watch guards easy to follow.
They next come upon a chamber:
This rectangular chamber shows no earthquake damage, possibly because of the buttresses and columns supporting the walls and ceiling. Four pools of liquid are set into the floor — one blue, another green, a third clear, and the last cloudy. Carvings on the walls seemingly depict the pools, and show robed figures submerging themselves within. At the far end of the chamber stands a double door with a large, ornately carved lock.
They investigate the pools don’t seem super deep, about 10 feet with sheer sides. With a successful arcana trap they get the impression of transmutation from the pools. Same with the door.
After an unsuccessful lock-picking attempt several of the party are transformed into poisonous snakes for 3 rounds and are compelled to attack the nearest creature to them.
Kosh, in snake form, gets tossed into the clear pool. With a successful Intelligence saving throw she avoids damage as the infinite possibilities of the multiverse seep into her brain. She gained clarity of mind that grants advantage on Intelligence, Wisdom, and Charisma checks and saving throws until the end of her next long rest.
After the snakes return to normal, Garz goes into the blue pool but fails his save as images of horror overwhelms his mind. He has visions of terrible calamities such as rotting flesh, crumbling edifices, and political speeches. This trauma imposes disadvantage on initiative rolls until the end of his next long rest.
Daja goes into the cloudy pool and makes a successful wisdom check to endure the intense itching from the acid and gains resistance to acid damage until the end of his next long rest.
Eric jumps into the green pool and fails his Constitution saving throw and takes poison damage and gains vulnerability to poison damage until the end of his next long rest.
As Eric goes under the green water, a silver key studded with polished red garnets appears in midair in the center of the room. In addition to opening the door, the key is worth 25 gp.
The adventurers take a short rest before proceeding through the door.
(I hope I got the right people in the right pools – let me know if I messed someone up.)