We're back in Sigil, on the upper level of Illustrial's sanctum, and it's quiet. Our connection to Vecna is stronger than ever.
A pretty glass bell sits on the table with a note: "ring me". Gnarls checks it for traps and rings it, and a letter floats in. Illustrial has been keeping up with the events on Pandemonium, and fears she may have been too late. She's returned to Silverymoon to heal, and Tasha is gone too; Vecna's influence is spreading. She leaves us weapons, potions and her luck: a rod of power for Gnarls, a berserker's glaive for Jain, elven chain for Fell, and an efreeti bottle for Sugar.
After a long rest we head back to Pandemonium. The place is flat for miles, except for one thing: a skull of black obsidian a thousand feet tall, set into a cliff, with glowing eyes. Each of us is tempted on the way in. Sugar sees a goblin throne and a harem, Fell an elven forest without end, Gnarls a deafening rock concert in a Greyhawk amphitheatre, and Jain a warrior queen's seat on the Rock of Baal. We keep walking into the wind.
Vecna threatens us all the way in, and then the ground breaks open: thousands of skeletons and wraiths. Gnarls answers with the radiant power of rock, sunlight blasting them back. Jain carves a path at incredible speed, skeletons flying from every blow. Sugar slips through a shadowy trench, and Fell draws them off and tumbles through the army untouched. We reach the skull and shut the door behind us.
Inside, a narrow glassy corridor full of whispers and the smell of blood and copper. Four flameskulls don't last long. Gnarls realises we're inside something: a giant vein. It opens into a vast space of bridges with air moving up from below. Everyone flies up except Jain, who jumps bridge to bridge, and then a storm of bones blasts up from beneath and throws her and Gnarls into everything. They teleport out, a bit worse for wear.
Through a portal is the ritual: a pool of blood, undead goblin things wandering, and sleepers trapped in nightmares while their blood and secrets are harvested for Vecna. Worse, we know them: Sugar's family, Gnarls' brother and parents, Fell's elves, Jain's battle sisters. In the ensuing fight Jain sees her own death, throws up, and falls unconscious. Once it's won, Gnarls destroys the glyph on the ceiling with a 9th-level dispel, and the sleepers wake up, confused.
Jain uses the Chimes of Unmaking to send them all back to their home planes, punching them in the face as necessary since they have to be close to death.