Rekindling an old flame dating
The siblings Grob Gob Glob Grod and Magic Man are recognized as existing, the former of which is seen as a demigod.Magic Man marries Margles but she is stolen by Golb, a devil-like figure.
In trying to prevent his dad from escaping, Finn loses his right arm and the Grass Blade. Maja summons Darren using the power of Princess Bubblegum's shirt and attacks the Candy Kingdom.The Lich, having bathed in the blood of the Citadel Guardians, reverts to an organic and childlike creature. Pig adopt The Lich as a child and name him Sweet P. Root Beer Guy dies, but Maja is defeated by Finn, Jake, and the Ancient Psychic Tandem War Elephant.A comatose Maja is taken into the care of the Elephant, who is now free to do what he pleases.Simon Petrikov obtains the ice crown and Enchiridion from an archeological dig.He puts on the crown as a joke but it begins to change his emotions and begins to turn him into the Ice King. It's unstated when in time pre-Mushroom Earth actually is.Instead of battling an evil wizard, the Ice King comes off as crazy in sympathetic ways rather than malicious ones.
They save princesses and the blatant over-abundance of princesses is perhaps the most ridiculous aspect of this show, the minor princesses often providing small amounts of romantic comedy.
He abandons Marceline and leaves her in the care of an unknown person. (and it's unknown how or when the other kingdoms formed, when the creatures, monsters and/or humanoids of Ooo formed (or where they came from), when was Billy born, or when did he imprison The Lich in the candy kingdom's tree.) Bonnibel and Neddy Bubblegum are born from the Mothergum.
The world has been mutated enough for there to be radioactive creatures and wreckage. Both find a tree which gives life-sustaining juice. Angry at her father, Marceline returns him to the Nightosphere, leaving Marceline independent on Ooo. Marceline and Ice King meet for the first time in years. Finn wishes that the Lich never existed, thus creating the Alternate Timeline (see Alternate Timelines).
This show's plot could be reduced to "two buds hanging out in any way possible".
In reality, there's no accurate way to summarize this mess... The show relies heavily on use of fantastic elements (swords, monsters, princesses) in a fantastic setting (divided into kingdoms of fire, ice, candy, etc.), and many tropes consistent with the genre of High Fantasy. Many of the characters are twists on stock characters.
Finn and Jake find the physical body of Prismo and return it to him in order to gain entrance to the Citadel.