|RIDICULOUS FOLLY. INEXCUSABLE.|
|Even though sloppy is fine, it might be a bit of a good idea to arrange this particular page because, to be quite frank, as it is right now, it is just absolute garbage.|
The Great Undoing is a mysterious event linked to the end of the the trolls' universe. A ~ATH program on a server far beyond Alternia's network is set to summon Lrd English upon the Great Undoing. Doc Scratch, first guardian of Alternia and an ally of Lrd English, has been paving the way for his arrival, and will continue to do so until the Great Undoing.
The Great Undoing ends up being the culmination of both sets of players' respective failures at the game, specifically the simultaneous destruction of both the kids' and the trolls' universes caused by iterations of Jack Noir. Identified by Karkat Vantas as "The Cancer," the embodiment of the kids' faulty universe and the series of destructive events experienced by both sets of players. The kids' Jack exits the session, hiding in a time capsule on the meteor that would go on to seed the Frog Temple that ejects him in 2422 just as the universe is dying of the Red Miles and the exiles prepare to escape the universe. Killing the Writ Keeper, Windswept Questant and Aimless Renegade and wounding Wayward Vagabond, he exits the universe using a machine in the WV's capsule, arriving in the trolls' session (as we'd previously seen.) After destroying the trolls' planets, Prospit, Derse, and all the trolls' remaining dream selves, he unleashes a supercharged Red Miles attack on the kids' universe from the outside (causing the Red Miles he himself fled Earth from).
On Alternia's green moon, Spades Slick confronts Snowman with the pistol given to him by Doc Scratch. Both having nothing left to live for, she tells him to draw and he shoots her through the heart, destroying the trolls' universe due to the powers given to her by Doc Scratch.
Unbeknownst to Dave and Rose, The Tumor they are trying to deliver to the Green Sun to destroy it is a bomb containing both universes. Due to the unreliable flow of time in the Furthest Ring, the bomb's timer ticks down to zero before the sun's existence, creating the Green Sun as Doc Scratch had planned the entire time.
The server in the Furthest Ring activates the ~ATH program transmitting it to a "time pocket" inside the Green Sun, which contains the exploded mass of both universes, causing Doc Scratch's body to grow and transform into that of Lrd English, who teleports back in time to begin preparing for that very summoning.