The descendants find Finn's robot arm after trying to mess with one of the future guardians and tripping it. They take it to BMO which starts the backstory. PB rallies her troops, Marcy aides her but flashes back to her standing in front of the ruins of the mushroom war and says she knows how these things can end, and wants PB to dial it back, but PB doesn't. Finn and Jake, while on her side, want to make peace between the two factions rather than fight. Jake is neutral and is waiting for everything to blow over. Finn eventually gets PB to give Gumbald a second chance, but he attacks a banana guard from inside his cake robot. After this, Finn gets them together but they still don't see eye to eye. Finn says fuck it and throws the Nightmare Juice bottle onto the ground killing everyone instantly.
At least, that's what LSP thought. Now they're in dreamland where Finn and Fern duke it out as dreamland changes every so often, they fight as bears for a bit, as well as PB and Gumbald fighting as the warping continues. After a bit, it changes to PB living in Gumbald's place and Gumbald living in PB's place where they both see how each other went through things. This gets them to understand each other better and make peace. Jake chills with a Jermaine he dreamt up beside him and snacks on a sandwich together. At some point the grass demon shows up, Finn doesn't really like it, and Fern is told by it that killing it kills him, but he stabs it with a chair anyway and it and him die, Fern not feeling so good into the wind. Finn is sad. As PB and Gumbald settle on a truce that will result in him getting his own Candy Kingdom, they're jolted awake right before they shake hands by Lolly, who splashes dumdum juice on Gumbald, turning him into Punchy. She tells PB that Gumbald isn't one for diplomacy, and they make a truce together instead.
