I can't believe I forgot to post about this over here, but I'm writing a free 4e Planescape adventure (for levels 11-13) over here: http://www.enworld.org/forum/d-d-4th-edition-discussion/321736-writing-d-d-4th-edition-planescape-adventure-community.html
I know most folk here prefer older editions, but there's quite a bit of old school feel in the adventure, it's sort of a sandboxy heist that revolves around stealing the Book of Lies from Dispater's Iron Tower, lots of Planescape themes and flavor. I'm looking for feedback and anyone interested in contributing to it. 
Just a critique, but I'd be wary about sending adventurers to a quasi-deity's stronghold for raiding for several reasons.
1. These strongholds tend to be HUGE. Usually miles long and/or high. I cannot stress this enough. To give you an example, I calculated how many floors would be in the Chisled Estate, Cryonax's stronghold, and IIRC it was around 40. 40 friggin' floors.
2. Quasi-deities are well... more like demigods or lesser powers within their strongholds. This means they can do all manner of horrible things to the PCs, such as remove all the doors/windows/etc. from a room they're in, or make them walk in circles. Now, if that quasipower is absent from his realm, that is another story, but you still have to deal with #1.
3. Whatever you do, DO NOT assign the PCs a quest that involves slaying a quasipower within its own stronghold (this includes killing The Lady within Sigil). It is impossible, and even quasipowers possess far, far more power within their stronghold (for instance, the Elemental Princes can probably use any spell with their element subtype or with effects dealing with their element while within their stronghold. Not fun for the PCs. Not to mention that most Quasipowers, unlike their aspects *the aspects are typically what is statted in the books*, possess abilities that allow them to bypass resistances and immunities to certain types of damage-- for instance, Archomentals possess "primal energy", which ignores energy resistance and inflicts half damage to those with energy immunity. Archfiends and Celestial Paragons, Bastions of Law, etc. would possess similar abilities related to their alignment.)