Alright, new addition to the Theory Vote pool. Something that Mathilde knows that really needs to be communicated
[X] THEORY: Based on Guild and Dwarf secrets we can tell that Karag Dum is slowing the spread of the Chaos Wastes.
Waystones absorb magic, making the world more real and less like the poles. The official line is that they're all elven things that route it into a great vortex for safe disposal. We know that the energy can actually be put to use, and that Dwarves have their own network, but there's no reason to doubt that they increase the firmness of reality and hold back the wastes.
[X] THEORY: There's some sort of strange illusion magic going on, and it's not visible even to extremely good mage sight. Out of all known sources of magic only Dawi Runes are capable of that - so the works of Dawi Runesmiths are still in use.
[x] Action: Pray for guidance. In this realm reality is more malleable, perhaps our gods will be able to reach us more easily here.
[x] THEORY: Karag Dum is using a fake Morghur to make the real beastmen fight for them.
[x] Action: Look for the source of the desert.
[x] THEORY: That's not Morghur. Morghur constantly changes his surroundings, Morghur does not make reality more stable near himself, Morghur does not display affection, Morghur would never stay here unless he was bound, and if he was bound he'd be struggling constantly to get out. The shuddering of reality can be faked by Runesmiths if they wanted.
[x] ACTION: Demand the Runesmith in the Morghur Fursuit presents Borek so you can scream at him for not mentioning he was taking you to the Capital of Dwarven Illusion Craft. You would have brought more ink and paper.
[x] THEORY: The dwarves of Karag Dum are alive and uncorrupted by Chaos, but have resorted to truly drastic measures to survive, probably undertaken by their controversial "Rune Masters", which involves having these beastmen or beastmen-appearing creatures defending the karak for the dwarves. We can assume that this is all in favour of the dwarves by Morghur's easy acceptance and non-destruction of Borek as well as Borek's mutual acceptance of the beastman. The idea of Rune Masters being critically involved is the certainty that some form of magic was used to create this whole situation, including the odd weather, and the Rune Masters' lack of corruption is supported by the lesser level of ambient dark magic in the area, even directly around Morghur himself.
[x] ACTION: Project a message in the air with magic asking for a Parley.
[x] THEORY: Karag Dum converted their Rune of Valaya into a Rune of Valaya's Vengeance, and used it to burn away all of the surrounding Dhar, causing a cataclysmic explosion and presumably wiping out whatever threat they were facing. But having lost their Rune of Valaya, they no longer had a defence against the Winds of Chaos, and they knew it. They could not simply die, for they had a critical duty to protect their hold, for reasons that are secrets of my Guild and Karak Eight Peaks, and so they decided that if they could not survive to defend it as Dwarves they would no longer be Dwarves. They found a way for dwarves to become beastmen, and know that they must defend their Karak as though it were their herdstone. Pity them.
[x] THEORY: Morghur has been linked to Karag Dum's waystone, which is acting as a psudo-herdstone that is burning away Dhar instead of creating it. Morghur is possibly cleansed of Dhar, and sees dwarfs of Karag Dum as family. The waystone may have been the cause of the weird geography via Geomancy, and might be weaponized. Based on Boreks last words, this was a longstanding contingency plan held by the dwarfs of Karag Dum. He is ashamed because it's a desecration of one of the greatest relics of the Ancestor Gods, as well as binding the fate of Karag Dum to a Beastmen Demi-God.