Cascade begins with God-tier John on the Beat Mesa on Dave's planet, the Land of Heat and Clockwork, initiating the Scratch. There are monsters everywhere, so he uses the Windy thing to summon a bunch of tornadoes to kill a bunch of them and then uses the Warhammer of Zillyhoo to kill off a particularly big one. Smashes that sucker right in the face, one-hit kill, kapow and there's grist everywhere.
Now we go to Jade's planet, the Land of Frost and Frogs, where the Courtyard Droll finally managed to complete his mission and kill Jade, using stuff taken from Dad's wallet stolen from the Warweary Villein, since Jack was himself unable to kill Jade. Jack, because of the fact that he is prototyped with Jade's loyal dog Becquerel, flipped out over Jade's death and killed CD. Now we see him mourning over Jade's dead body.
Cut to another Jack, in the future, covered in blood and flying above Bilious Slick, otherwise known as
the Universe. He reaches out and performs his ultimate attack Red Miles and here's where everybody shat their pants because the fukkin screen expands to twice its size.
Red Miles begins thoroughly destroying the Universe and we see explosions and stuff as we zoom in on the Earth. Here we see two of the Exiles, the Peregrine Mendicant and the Aimless Renegade. Looks like AR has rigged up all the buildings to be exploded, he's holding the trigger box and turns it on.
Meanwhile in the Frog Temple we have the White Queen, er, Windswept Questant standing in front of the Lotus Time Capsule, which is about to bloom. It does and out from it steps the White King...or the Writ Keeper...holding one of Rose's journals,
Complacency of the Learned. The time capsule then resets and indicates that it is about to bloom in ten more seconds.
But before we get to see that, we're back on Jade's house. The mourning Jack picks up her dead body and takes off into the sky. Where does he take her? Why...her Quest Bed! Everybody starts rejoicing. He gently sets Jade down on the bed, then flies away. He flies, in fact, right into the Frog Temple while it is still flying on its meteor.
We watch as the Frog Temple meteor flies towards Skaia, into one of the portals, lands on Earth in the past, and eventually becomes the Frog Temple near Jade's house, and now we're back in the future where the Universe is being destroyed and the time capsule has ten seconds to bloom.
Of course, Jack steps out of the lotus and slaughters the king and the queen. Then he appears outside of the temple and approaches the Peregrine Mendicant. She raises her Regisword to fend him off, but Jack gets distracted as the Aimless Renegade blows up the Bec Head Base on top of the Frog Temple.
Jack starts approaching AR instead, who blows up the Eggy-Looking Base and then the Helipod Base. However, he hesitates when he gets to the Skyship Base because, as we are shown, the Wayward Vagabond is still inside. Unfortunately, this hesitation leads to AR's death. PM tries to attack Jack but he disappears and then reappears inside the Skyship.
Jack notices that the base has no fuel. He finds the fuel, a chunk of uranium, inside WV. He punches through WV, getting his arm all bloody in the process, to pull out the uranium and powers up the base with it. Then he uses a special teleporter to appear in the Trolls' session. Here he performs a whole bunch of atrocities, as seen in previous animations.
Meanwhile! Inside Derse's moon we have Dream Dave and Dream Rose, on their mission to take the Tumor to the Green Sun and destroy it. They killed the Draconian Dignitary, who attacked them. Dave and Rose fly down into the very core of Derse's moon where they find, of all things, their Quest Beds.
They open the Tumor and reveal a bomb, with a timer already set at around five minutes. We zoom in on the red cylinder and see the red universe (the Kids' universe) being destroyed by Red Miles. Then we zoom in on the blue cylinder and see the blue universe (the Trolls' universe).
It focuses on Alternia's green moon, where we know the Midnight Crew intermission took place. Standing on one of the buildings in the city we have Snowman and Spades Slick. "What are you waiting for? Draw, Spades," Snowman says. Spades, wielding Doc Scratch's gun, raises it and points it at Snowman.
Bang! He shoots Snowman right in the heart, splattering blue blood everywhere. We all know what happens when Snowman dies, right?
If you kill her you destroy the universe. Sure enough, the blue universe goes up in flames and starts falling apart.
Zoom out. Way out. Where are we now? Jade's planet again, LOFAF. We see the four pillars on the Quest Bed, we see Jade's body lying on the slab, we see the image on one of the screens in the Skyship Base fade out, and we see PM freaking out over WV's dead body. Then we focus on LOFAF again.
Hummingbirds surround Jade's body, just how fireflies surrounded John's body on his Quest Bed. We switch focus to Skaia, under attack by the Reckoning. Davesprite and Jadesprite are standing on the ravaged Battlefield, watching as a meteor closes in on them. The Quest pillars light up, we see the symbol of Space as Jade ascends to God Tier. Jadesprite is taken over by God-tier Jade, the Witch of Space.
She uses her awesome God-like abilities to shrink the meteor down to the size of a pebble and then fly on one of the Prospit battleships. She shrinks down the entire Battlefield, Davesprite included. Then she flies over to her own planet. Meanwhile, we see John on the Beat Mesa, having finished the Scratch. Then we see PM, dragging WV's dead body and mourning his death. PM notices the White Queen's ring, which had been in the possession of WV. She reaches down to take it.
Back to God-tier Jade, she picks John up from LOHAC and puts him on the battleship she's flying. Then we focus on Derse's moon again, where Dave and Rose are. Now we see Jade again, shrinking down and collecting all four of the Kids' planets. The timer appears. 45 seconds left. PM is putting on the ring, the Beat Mesa is descending into Skaia, Dave and Rose are watching as the Tumor counts down, the Universes are being destroyed, Jade is forming a window into another space.
Now, Gamzee. The most important character in Homestuck? He's watching Jade's lab on his computer while inside of it Jadesprite freaks out at her own existence.
TC: that's all motherf*ckin done white texted bro.
TC: NOW WHAT?
TC: oh yeah?
TC: AND JUST WHAT THE MOTHER F*CK IS IT
TC: that we motherf*ckin are?
TC: :o?
S u c k e r s.
Wait, WHAT?
Countdown hits zero. There's Derse's moon, with the Tumor inside, but where's the Green Sun that they're supposed to be destroying? Tumor explodes—oh, there's the Green Sun! Doc Scratch played them all along. Apparently they just
created the Green Sun, not destroyed it. Somehow.
God-tier Aradia and a dream-bubble Sollux are hovering in space right next to the newly-formed Green Sun. Remember what they were waiting for? First for two humans to arrive, and then for the rest of the trolls (minus Sollux, who supposedly is going to arrive a corpse).
We see Jack now, outside of the Trolls' universe. Then we see the Trolls, on the meteor base. They look up and see the Green Sun, all except for Sollux and Terezi of course, who are blind—Karkat has to correct where she's pointing, since she's a bit off. Then Sollux does something. Remember his ancestor, who was forced to use his telekinesis to fly the Condesce's flagship? Sollux flies the meteor towards the Green Sun but the strain is too much for him. He dies in the process, sacrificing himself for the rest of the trolls.
Jack notices something happening on the Ultimate Reward platform behind him, where he first entered this universe. Someone else is coming through. Meanwhile, rising out of the Green Sun, Dave and Rose ascend to God Tier and meet Aradia and Sollux. Back to the Ultimate Reward platform, the Peregrine Mendicant has come seeking revenge. In the background we can see the trolls' meteor nearly reaching the Green Sun.
Now Jade's window again. Once it's fully created, Jade flies her battleship, containing the Battlefield, the Kids' planets, and John, through.
and that's the end.