Fecaurum - Abyss
This abyssal layer appears to be full of rare treasures, but these treasures are in fact partially real illusions (although unlike most partly real illusions they are not based on shadow). When removed from the layer these treasures revert to their physical substrate, which is literal bull$#!+. In the case of magic items, they also turn to bull$#!+ if their charges run out (which may happen randomly to an item that should still have charges left or even to one that should never run out of charges). The illusions are very convincing and only someone extremely strong willed and wise could possibly see through them while on the layer.
Murder-Con
A seemingly infinite convention center holds a seemingly endless convention dedicated to the art of murder and warfare. The convention center exists simultaneously on Gehenna, Pandemonium, and the Abyss
The Umbrella - Far Realm (or possibly Faerie?)
A small chamber where an umbrella is embedded in a mound of wax. Acid congeals on the umbrella and drips up into the sky. The umbrella is semi-intelligent and insults anyone who comes near
Pilabum City - Ravenloft
A city banished to the mists for its use and abuse of blood magic. The city had ubiquitous magic in every household, but it was powered by the mass slaughter of intelligent magical beasts, whose blood was pumped out into households and shops to recharge the magic items there. The power plant did not make it to the mists, and now the residents are eager to waylay outsiders and take their blood. The darklord is the inventor and popularizer of this system of blood magic, a powerful mystic theurge. This particular mystic theurge worships a dying-and-reviving vampire god whose renewed undeath brings the winter.