The PCs erected a magic circle around the Mausoleum of the Raven Queen, in order to prevent anyone from entering it and potentially learning her true name (backstory
here); then rested; then scried on the tarrasque, which they knew to have recently begun marauding in the mortal world, identifying its location and noting that it was being observed by maruts. They decided that, to return to the mortal world to confront the tarrasque they would first teleport to their abandoned Thundercloud Tower, and then take that with them through another conjured portal and fly it to where the tarrasque is.
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When the PCs step through the portal from their resting place to the top of the tower, they find that it is not where they left it -
on the disintegrating 66th layer of the Abyss - but rather in the palace of Yan-C-Bin on the Elemental Chaos. This brought the PCs, and especially the chaos sorcerer, into discussion with the djinni who had retaken possession of the tower and were repurposing it for the coming Dusk War. Mechanically, this situation was resolved as a skill challenge.
Sirrajadt, the leader of the djinni, explained that the djinni were finally breaking free of the imprisonment they had suffered after fighting for their freedom the last time (ie with the primordials against the gods in the Dawn War), and were not going to be re-imprisoned or bound within the Lattice of Heaven, and hence were gearing up to fight again in the Dusk War. He further explained that only Yan-C-Bin (Prince of Evil Air Elementals) and the Elder Elemental Eye could lead them to victory in the Dusk War.
The PCs both asserted their power (eg the paladin pointed out that the reason the djinni have been released from their prisons is because the PCs killed Torog, the god of imprisonment), and denied the necessity for a coming Dusk War, denouncing warmongers on both sides (especially the Elder Elemental Eye, whom Sirrajadt was stating was the only being who could guarantee the Djinni their freedom) and announcing themselves as a "third way", committed to balancing the chaos against the heavens and ensuring the endurance of the mortal world.
Sirrajadt was insisting that the PCs accompany him to meet Yan-C-Bin, declaring that mercy would be shown to all but the sorcerer. (The reason for this is that the chaos sorcerer - who is a Primordial Adept and Resurgent Primordial - has long been a servant of Chan, the Queen of Good Air Elementals, who sided with the gods during the Dawn War and is resolutely opposed to the Prince of Evil Air Elementals; hence the sorcerer is a sworn enemy of Yan-C-Bin.) As the PCs continued to debate the point and explain their "third way" reasoning (mechanically, getting closer to success in the skill challenge), Sirrajadt - sufficiently unsettled by their claims - invited them all to resolve the matter in conversation with Yan-C-Bin, who moreso than him would be able to explain the situation. The PCs therefore went to meet Yan-C-Bin himself, as guests and not as prisoners - not even the sorcerer.
Yan-C-Bin greeted them, but mocked the sorcerer and his service to Chan. There was some back and forth, and some of the same points were made. Then the PC fighter/cleric Eternal Defender, who has
recently taken up the divine portfolio of imprisonment (which position became vacant after
the PCs killed Torog), spoke. Both in the fiction and at the table this was the pivotal moment. The player gave an impassioned and quite eloquent speech, which went for several minutes with his eyes locked on mine. (We tend to be quite a causal table as far as performance, in-character vs third person description of one's PC vs out-of-character goes.) He explained (in character) that he would personally see to it that no djinni would be unjustly imprisoned, if they now refrained from launching the Dusk War; but that if they acted rashly and unjustly they could look forward to imprisonment or enslavement forever.
The player rolled his Intimidate check (with a +2 bonus granted by me because of his speech, far more impassioned and "in character" than is typical for our pretty laid-back table) and succeeded. It didn't persuade Yan-C-Bin - his allegiance to the Elder Elemental Eye is not going to be swayed by a mere godling - but the players' goal wasn't to persaude Yan-C-Bin of the merits of their third way, but rather to avoid being imprisoned by him and to sway the djinni. Which is exacty what happened: this speech sufficiently impressed the djinni audience that Yan-C-Bin could not just ignore it, and hence he grudgingly acquiesced to the PCs' request, agreeing to let the PCs take the Thundercloud Tower and go and confront the tarrasque - but expressing doubt that they would realise their "third way", and with a final mocking remark that they would see for whom the maruts with the tarrasque were acting.