Finn and Jake contend with a mysterious, but familiar, new being.
Tropes:
- Call-Back: Reveals what happened inside the Finn Sword when he/it was stabbed in "I Am A Sword".
- Crazy-Prepared: Princess Bubblegum admits she was working on Finn's new artificial arm since the last time he lost an arm.
- Giant Spider: The "curse" within the Grass Sword is about the size of a football (relative to Sword-Finn) and looks like a cross between an octopus and a spider.
- Overly Long Gag:
- The Banana Guard calling for the big ambulance, and having a long Newhart Phonecall with the guard at the other end.
- Jake trying to get Grass Finn to look at him while he scolds him.
- Sense Freak: Grass Finn becomes incredibly happy as his senses "return".
- Sequel Episode: The episode takes place after the Season Seven finale, "Reboot".
- Shout-Out: The hand-like "curse" moves like a face-hugger and wraps Sword Finn up like Shelob, though it's much smaller and Sword Finn's "cocoon" is much more spacious.
- Spot the Impostor: Subverted. Grass Finn asks Jake to identify the real Finn. To Grass Finn's surprise, Jake immediately picks Original Finn.
- Tell Me Again: Parodied. After Finn recounts the story of what happened after the fight with Susan, Princess Bubblegum asks him to say it one more time, just to make sure. At this point the show cuts away to Grass Finn at the treehouse.
- Tomato in the Mirror: Grass Finn truly believes he's the original Finn.
