In "Mystery Dungeon," Ice King kidnaps Tree Trunks, Neptr, Lemongrab, and Shelby to help him get through the labyrinth which leads to the Magi. Once they make it there, Ice King throws his Fionna and Cake fanfiction into the Magi's flames, hoping all of his imaginary characters will come to life. Instead, the book itself is brought to life by the Magi. After Ice King insults him, the Magi flies out of the labyrinth by phasing through the ceiling.
To avoid bringing anything else to life, the Magi dons oven mitts and buries himself underground in "Little Dude." However, a flower grows out of his head and touches Finn's hat, bringing it to life. Finn dubs it "Little Dude" and takes it home. That night, the Magi sneaks into Finn and Jake's house looking for the hat. They ambush him, and he reveals everything that he brings to life becomes evil due to his bad relationship with his father.
Meanwhile, Little Dude travels to the Candy Kingdom, possesses a citizen, and starts wreaking havoc, eventually managing to take control of a Gumball Guardian. The Magi learns that if he thinks about his mother, whatever he brings to life becomes good. The various objects he brings to life team up against their "gross brother" and defeat him. At the end of the episode, the Magi takes back the objects' spirits, including Little Dude's. Jake, however, thinks that Finn's hat "deserves to come back good," so the Magi re-animates it. Finn then gives it to the Magi to raise as his own, who promises treat it "way better" than his father treated him.
In "Thanks for the Crabapples, Giuseppe," the Magi takes a road trip with Ice King, Abracadaniel and a number of other wizards/magical creatures, including Little Dude. He appears to be on good terms with Ice King and the other wizards, who seek to perform a unique spell, create a new school of magic, and form their own secret society. Over the course of the adventure, he briefly steers the bus, though he says he is not a confident driver, and attempts to save the wizards when the bus sinks in a swamp by bringing it to life with his touch and the word "Mommy!" However, the now-living bus can't swim, so the Magi turns it inanimate again by touching it again and saying "Mommy" backwards. His head is briefly switched with Ice King's thanks to a potion, but it is on his body again at the end of the episode, where he and Abracadaniel are shown as part of a society based on their experiences on the trip.
In "Friends Forever," Ice King invites the Ancient Sleeping Magi of Life Giving over with the ulterior motive of tricking the Ancient Sleeping Magi of Life Giving into bringing his furniture to life so it will be best friends with the Ice King. The Ancient Sleeping Magi of Life Giving resists this, but is ultimately forced to do so by Ice King. After the now-living furniture tells Ice King some uncomfortable truths about himself, he destroys most of it, but despite his treachery, the Ancient Sleeping Magi of Life Giving is lonely enough that he is okay still being friends with the Ice King.
He wears a light purple robe with dark purple bottom and sleeves. He is covered in brown fur and has very long fingers and fingernails. A flower grows on his head, and his feet have three toes. He also has red eyes.
I'm sorry, that's just the way my magic works. Papa always said I was a bad wizard. Right, Papa?! "Baby's a bad wizard"! A bad wizard, huh?! You're a bad wizard! I'm a bad wizard!
I LOVE MY MOMMY!!
Inspire us, water nymphs!
- In "Little Dude," the Magi returns with a flower on the top of his head, which he claims grew out of his head when he buried himself.
- In the time between the Magi's first and second appearances, Pendleton Ward created another character named The Cereal Master who also had bad memories of her father in his smaller web series Bravest Warriors.
- "Magi" is the plural of the Latin word (though it has been adopted into English as well) "Magus," meaning "magician" or "wizard." It can also be used as a plural for "mage," which has much the same meaning.
- In the storyboard for "Little Dude," he is referred to as "Dirt Wizard."
- Magus also appears In Nintendo All Stars Summer Camp Special On you Tube Along With Princess Bubblegum.