I know its been a while since I've talked about it, but I've been working on it--honest. I have the basic layout I'm going for in mind, but there a lot of things I feel I need help on.
Here's a summary of what I intend so far.
The PCs start off by getting belched out of a portal that's found itself at the bottom of a cistern; a tall (50 foot according to the map) cylinder with jutting pipes, valves, dials, and other pressurized equipment. Above them is a large pipe that leads out (40 feet overhead), and behind them is a room with several valves they can turn to adjust the water drainage and water intake.
Its pretty simple to solve: Turn on the drainage and the PCs can float up to the exit. Alternately, Spider Climb or psionics would be an acceptable solution, whatever floats your boat. If the PCs use the water solution, ghouls and ghasts start flowing in through the pipes within a few rounds and start attacking, trying to drag the PCs under and drown them for undead chow. The PCs can run like hell or fight (if they have a good cleric, they have a half-decent chance), whatever. Once they escape, they enter the sewers:
Otyugh attacks at B, grabbing and dragging into the Blackwater. If the PCs get by this, they have a clear shot up to the Temple of Aoskar, in the middle of Ilgrave (slightly to the south).
Ignore the area names for now, going to change them later.
Aoskar's Temple is a safe region. Unlike the rest of the city, it isn't under attack by the Undead or the Hollow Ones (see below). Its taken care of by an elven cleric of Aoskar by the name of Rupert (the Coward) who is terrified of the undead and refuses to leave the temple's consecrated grounds. He informs the PCs of the current situation and asks their help.
The Hollow Ones are what's left of the city's citizens. They survived the cataclysmic events that destroyed the city (see below) by infusing themselves with Blackwater; they've drank it so many times they've become literally hollow inside (upon death, they shatter like porcelain). Most of them are barely sentient and they're lead by an incredibly willful Githzerai who wants to use the Blackwater to invade the Astral and pump it into the bodies of Dead Gods to ressurect them.
Blackwater is negatively-charged water that brings back the dead within a day of their submergence in the water. It was created to supply cheap labor to the city; the Mages set it so whatever dead was ressurected by the water would instantly begin searching for more dead to throw into the water, increasing their number. When the dead ran out of corpses, they started making them.
Anyway, Rupert begs the PCs to help him destroy the Hollow Ones before they up and do something crazy, but since he's Lawful Good he won't force them to. If they just want to leave, he'll tell them how--the portal out is in the Air Ward, in a place known as the Bellows. Its a massive theatre/concert hall with the vast majority of it being pipes and bellows used to power the massive organ which would long ago fill the city with music. The Hollow One presence there is very strong and they'll attack anyone who comes near.
Additionally, Rupert recommends the PCs visit Daelwick's Tower in the Earth Ward, a crazy dwarven mage/alchemist who was responsible for the creation of Blackwater. He hasn't heard from him for several centuries, but by the look of the lights that flash in the tower at times it seems possible that Daelwick may still be alive, and may still be willing to help (neither are true). If the PCs go, they're taunted the whole way by statues of Daelwick and Magic Mouth spells as well as an assortment of odd planar traps and dimensional spaces, until they finally arrive at the top to find Daelwick long dead, his research unfinished. As a reward they can collect a few magic trinkets and a salve that offers immunity to Blackwater for a few hours after one application.
Rupert also recommends the Fire Ward, because although the Furnace--a giant metallurgy factory for weaponry, golems, armor, and tools--has mostly had its stuff stolen, there may still be some heavy artillery they can use against the Hollow Ones. Here in the Furnace the main threat is the environment (incredibly hot) and the minor fire elementals who have broken free of their magical bonds and now roam free.
Rupert wants the PCs to go to the Water Ward and attack the Hollow Ones there, where the Githzerai sits in the Sunken Temple, preparing more Blackwater for his invasion of the Astral--specifically, he recommends they hit the Pump first (a separate building), where water was summoned from the Water Plane and filtered into the Temple for purification (now desecration). Doing so would mean breaking off the flow of water to the city, making the encounter with the Hollow Ones substantially less dangerous. The Pump is a nerve-wracking experience though, with lots of near-drownings underwater as PCs struggle to turn off valve after valve beneath the surface of Blackwater.
If PCs kill the Githzerai leader, the Hollow Ones begin to fall apart in a matter of hours. They were held together only by his sheer will, and once he's slain there's nothing more left to keep them working with one another. They begin shattering or just attacking anything they see, and leave their posts.
OKAY. With all that said, here's what I need help with: Designing these areas, ideas for these areas, ideas to make this more Planescapian (am I crazy for thinking that this just doesn't feel... Planescapey enough?), and maybe someone who would be so kind to tell me when my stat-blocks and encounters are just way-crazy out there hard.
Responses would be appreciated. I'll start posting some of my write-ups for the areas and encounters here soon.