In the Candy Kingdom hospital, Princess Bubblegum tries to heal Starchie of a cold with a serum, but Starchie is unwilling to be healed unless by means of magic. Princess Bubblegum asks Nurse Pound Cake to hold him down, but the nurse declines because she says her uncle, a magic worker, once cured her of her sadness. Exasperated, Princess Bubblegum then explains that magic is just science "presented like mystical hoodoo." She proceeds to mock magic, which causes Nurse Pound Cake and Starchie to be offended. She relents, seeing how upset they are, and promises that she will go to Wizard City to get a cold spell. She walks out into the hallway where Finn and Jake are waiting, and after explaining the situation to them, they are bummed out because Starchie's graveyard secrets workshop would be canceled. However, they seem to agree magic would work, but say trespassers would get killed in Wizard City. Princess Bubblegum employs the help of Finn and Jake, telling them to dress like wizards and meet her at the entrance of the city.
Finn and Jake stand facing a tall wall of rock, and Jake confirms from a map that this is the entrance. Jake stretches upward to look over the wall, but says there's nothing but "more mountains." Finn tries to trick the wall by pretending to give up and walk away, but when he turns back around and runs at the wall he just hits his head. Princess Bubblegum walks toward them saying she got the password from the Ice King, and holds up a tape recorder, explaining that the wall can only be unlocked by the voice of a wizard. She plays the tape, and they all listen awkwardly as Princess Bubblegum yells at Ice King for the password, even hurting him in some way until he surrenders. He says the password is "Wizards Rule," and at these words the rock wall disappears, revealing Wizard City. Finn is astounded by the "magic," but Princess Bubblegum is unimpressed, saying it is just "a vocal registry rigged to a vibration modulator" and that they can get through because "the density is all wobbled." Jake says "boo" and stretches into a five-pointed shape, asking how she could explain his ability, but she offhandedly calls it a "mutation."
While in Wizard City, the group comes across what they guess must be the Wizard City police interrogating a man who allegedly impersonated a wizard and purchased magic items from the store they are all standing just outside of. The police pull up their blindfold-hats, unmasking beams of golden light that hit the man and transform him into a hollow stick as a sentence for his crimes.
Finn, Jake, and Princess Bubblegum hurriedly rush into Ron James' Spell Palace and order a cold spell. The man behind the counter presents a crystal bottle. Bubblegum asks how the spell works, to which the man behind the counter responds, "it works by magic. It's a spell." Bubblegum is hesitant to buy it without any information, and starts arguing with the man, demanding what the contents are made out of. He then screams "YA'LL IS FAKES! and presses a red button behind his counter that calls the police. An alarm bell sounds as the police crash through the shop's window using the wooden sticks they carry, and Princess Bubblegum grabs the cold spell and escapes out another window, followed by Finn and Jake. She runs over rooftops and through the city, but cannot seem to lose the police, who run through a crowd, pushing down wizards left and right. Finn asks Jake if Princess Bubblegum is naked, due to the way her wizard costume looks, but Jake tells him not to make him feel "any more awkward."
They come to a dead end, but Abracadaniel comes out of a door that appears in the wall, carrying out what seems to be bags of trash. Despite his weak protests, Finn forces Abracadaniel and the others into the door, and it closes quietly before the police can get them.
In a cave underground, Bufo, the Laser Wizard, the Forest Wizard, and a hologram of the Ice King are preparing a sacrifice of Abracadaniel when he returns with Princess Bubblegum, Finn and Jake in an elevator. The wizards confront the group, yelling at Abracadaniel for letting the others into their "secret society." When Finn and Jake plead with the wizards, the wizards threaten to kill them, but they are interrupted by the police, who try to arrest the wizards for "harboring non-magic users." They escape using a force field, but leave Abracadaniel. Before the police can kill Finn, Jake, Princess Bubblegum and Abracadaniel, Princess Bubblegum removes her costume and orders to talk with the Grand Master Wizard, as ruler of the Candy Kingdom.
In his palace, the Grand Master Wizard speaks to the group atop a giant bubble, and expresses his disappointment with Princess Bubblegum and Abracadaniel. However, he says that they can go if she says "wizards rule." She refuses, due to her belief that magic is just science, and gets all four of them locked in wizard jail. During breakfast the next morning, Abracadaniel challenges Princess Bubblegum to an "honorable prison stabbing to the death." Princess Bubblegum defeats Abracadaniel, but refuses to kill him. Finn throws Princess Bubblegum the cold spell, which is really just a spell that releases cold air, instead of a cure for sickness.
Back at the hospital, Abracadaniel pretends to use healing magic on Starchie. As he is distracted by the magic, Finn holds him down as Princess Bubblegum injects Starchie with the green healing serum from the beginning, ending the episode.
- Ice King (voice in a tape, and using an invisibility spell)
- Nurse Pound Cake
- Stranson Doughblow
- Ron James
- Laser Wizard
- Forest Wizard
- Grand Master Wizard
- Huntress Wizard (cameo)
- Naked Wizard (cameo)
- Flame Lord (cameo)
- Old Wizards (cameo)
- Lady Wizard 1 (cameo)
- Lady Wizard 2 (cameo)
- Brain Wiz (cameo)
- Leaf Man (debut, cameo)
- Wizard 7 (cameo)
- Wizard 8 (debut, cameo)
- Wizard 9 (debut, cameo)
- Wizard 10 (debut, cameo)
- Wizard 11 (debut, cameo)
- Wizard 12 (debut, cameo)
- Wizard 13 (debut, cameo)
- Wizard 14 (debut, cameo)
- Wizard 15 (debut, cameo)
- Wizard 16 (debut, cameo)
- Wizard 17 (debut, cameo)
- Wizard 18 (debut, cameo)
- Wizard 19 (debut, cameo)
- Wizard 20 (debut, cameo)
- Wizard 21 (debut, cameo)
- Wizard 22 (debut, cameo)
- Wizard 23 (debut, cameo)
- Wizard 24 (debut, cameo)
- Wizard 25 (debut, cameo)
- Wizard Students
- Wizard Prisoners 1-70
- Princess Bubblegum considers Jake's shape-shifting powers a mutation, instead of actual magic. But she says also "All magic is science!" so the former may be just one more specific example.
- Finn never told Abracadaniel that he was Magic Fist, yet Finn assumes that he knows him.
- Finn describes a wizard spell called "Entanglement," a spell very similar to one used by druids in the popular MMO World of Warcraft.
- Finn talks about this in response to Princess Bubblegum's observation that the wizards' magic are based on "entanglement principles." This is likely referencing quantum entanglement.
- When Finn puts on his wizard costume, he has the Eye of Providence on his forehead. The eye, most commonly associated with Freemasonary, is sometimes said to be the eye of God looking down over mankind. It is part of the Great Seal of the United States and on the back of American one dollar bills.
- The discussion between Princess Bubblegum and the Grand Master Wizard resembles the situation occured to Galileo when he refused to recognize that the Earth was the center of the Universe and, as a consequence, Galileo was condemned to prison by the Vatican. In this situation, Princess Bubblegum represents the italian scientist while the Grand Master Wizard portrays the religious geocentric views defended by the Vatican in the XVI century.
- The fight between Princess Bubblegum and Abracadaniel, a formalized knife fight where the opponents are tied together at the wrist, is commonly portrayed in media as a means of violently resolving disputes between rival gang members and prison inmates.
- When Jake reveals the hidden flask he does so by opening his chest in the same fashion as Bender from Futurama does when revealing items he has stolen.
- Coincidentally, John DiMaggio voiced both Jake and Bender.
- Starchie says "Find me a wizard," which is a quote used in the film Just Visiting.
- Princess Bubblegum's wizard costume somewhat resembles the spacesuits worn in Bravest Warriors.
- Several connections to "Reign of Gunters" have been spotted from the episode.
- The title references a line from Ice King in this episode.
- Ice King seems to continue trying to join the secret group of Bufo, Laser Wizard, and Forest Wizard, this time by being invisible.
- Finn comments on how it is hard to find anything due to the lack of signs, which is similar to Ice King's claim in the same episode.
- The old wizards, as well as some apprentices from "Wizard" are seen in the city.
- Several wizards from "Wizard Battle" appear walking in the streets as a cameo.
- When Princess Bubblegum and Abracadaniel fight, one can see a character in the crowd who looks like Torcho from "Ignition Point."
- The escape made by Princess Bubblegum when she was being chased by the police was reminiscent of how thieves steal things in "City of Thieves."
- A guy from the cafeteria resembled the Cosmic Owl, who was first seen in "Prisoners of Love."
- When Princess Bubblegum says she was making fun of spells, the purple collar on her shirt disappears.
- When Abracadaniel is kicked after ripping a piece of Princess Bubblegum's hair with his fork, his fork disappears before he hits the ground.
- When Jake turns into an igloo, his prison uniform disappears.
- When Jake takes out the cold spell, Finn's prison hat disappears.
- In the scene where Nurse Pound Cake is talking to Princess Bubblegum, when viewed from the side, her eyes are on the side of her head instead of the front.
- Abracadaniel's pants change to shorts.
- Princess Bubblegum's hat disappears after it falls on the ground.
- Princess Bubblegum's tray and plate, along with Abracadaniel's hat, disappear before they begin fighting.
- After Princess Bubblegum ripped Abracadaniel's rainbow headband, one of his fingers became grey.
- In the European airing of this episode, the scene where Finn and Jake discuss about if Princess Bubblegum is naked, the image turned darker.
- This episode's original title was "Only Wizards Allowed."
- Despite being the 26th episode of season 5, "Wizards Only, Fools" is not the season's finale. It is one of numerous season 5 episodes produced after September 2012 instead of with the rest of season 5 in the recently passed summer, listed as a "season 5.2" episode.
- However, this episode was the mid-season finale for the fifth season.
- Adam Muto stated that Thomas Wellman originally storyboarded the ice magic turning into an ice bird that they used to escape the prison, but the scene was simplified for time.
- This episode is one of only two episodes to have won an Emmy Award, the other being "Puhoy."