The Multiversal Palace/Prison/Tomb of Buadak Sayung

     Here are the basic principles of the Palace Prison Tomb:

1.  In every universe of reality, there is, has been, or will be an entity named Buadak Sayoung.
2.  Whether by ill fortune, conspiracy, or deific loathing, Buadak Sayoung is doomed to be trapped in the Palace Prison Tomb.
3. By the nature of the Palace Prison Tomb, it is exceedingly difficult to escape.

            3a. This is even harder if you are Buadak Sayoung.

    Cool cool. So what? Well, since the multiverse is theoretically infinite and there is a Buadak in every one that is cosmically fated to be trapped in the Tomb, there have been a lot of them. The Tomb is a extraplanar space created, or maybe just existing without creation, for the sole purpose of keeping Buadaks inside, but at its outset it was much like outer space, only emptier. Then the first Buadak stumbled into or was banished to the Tomb only to find the space had nothing to breathe, and promptly died. This kept happening and eventually the sheer quantity of Buadak corpses in close proximity caused gravity to happen. The Buadak corpse-sphere grew to the size of an asteroid, then a small moon, and then to the size of a planet. Fun fact about the Tomb: Buadaks interact with the dimension in unique ways and never decompose past rigor mortis.

    That's a lot of death energy, and while it may be difficult to leave, it isn't all that hard to enter. Now, tunnels dug through the corpse-planet host all sorts of interlopers and tourists. Is there a surface? There must be, though nobody has tunneled far enough to find it. The little bits of air that accompanied every dead Buadak have also been adding up, and with the addition of flora and fauna adapted to the... unique environment of the tomb, it is entirely livable, if exceptionally dangerous. 

• Demons were among the first to find the Tomb, and they still come here to hang out and enjoy the ambiance in the sort of way that movie teenagers like to find parking lots and alleys to smoke. 
• Necromancers absolutely adore the Tomb, for obvious reasons. It's a great place to find materials, and if your creatures run wild, well, it hardly matters, does it? Many aspiring necromancers come to the Tomb raising undead in bulk for the practice, but can't be bothered to retain control of their creations, and as a result the tunnels are positively crawling with undead.
• Similarly, a college for those that would learn to build with the dead, Akrolaik University, has been founded in the tomb. Classes are half necromancy and half architecture and most students' final projects are to build some grand structure in one of the corpse-caverns of the Tomb. Sometimes graduates take their final project as their lair, but more often than not the building is simply abandoned.
• Since Buadak Sayung is an existential constant, the Tomb is currently the most stable known point in the multiverse to study the multiverse. An observatory has been built by and for the multiversal metastronomers that come to the Tomb to study, well, everything.
• A growing population of refugee hags fleeing persecution has been growing in one of the many blood-swamps of the Tomb, called the Bhel Grove Hag Commune. Mostly keep to themselves, except for an occasional ritual sacrifice. Lovely gardens, they grow a lot of tea.
• Fae are known to visit the tombs like condescending Japanese tourist stereotypes; they think the place is perfectly gauche and a putrid little hole of a dimension, but they're also kind of into that.
• The Tomb is still quite deadly, but in a different way than it used to be, what with the literally no oxygen issue, so now-and-again one of the Buadaks that comes through is a were-whatever and manages to survive and bite someone. Lycanthropy in the Tomb has thus become a serious health issue.
• Githyanki pirates have established a secret port city here, very hush hush. They seem to have the easiest time getting out, too.
• A Duergar treasure hunting expedition came to the Tomb some time ago and quite immediately found themselves stuck in, frankly, a horror story. Unable to get out, but able to contact home and ask for materials, they've since built themselves a small but defensible fortress spanning a chasm. They've been here for a few generations now and have gone a bit nutty.
• A particularly entrepreneurial imp has opened a tea house-brewery in the Tomb and the spot has become an after-work hangout for off-duty devils.