It Came from the Nightosphere

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Adventure Time - Season 2 - Episode 1

Adventure Time - It Came from the Nightosphere

About this Adventure Time episode:
Adventure Time - It Came from the Nightosphere is the 1st  episode of Adventure Time season 2.
In this Adventure Time episode, after Finn agrees to help Marceline record one of her musical compositions, she begins to sing a song, "The Fry Song", about the rift between herself and her father, Hunson Abadeer. Finn, feeling sorry for her, decides to summon her father from the hellish Nightosphere, failing to realize that her father is the domain's dark leader and that he consumes souls. He materializes before Marceline and Finn, attempts to kill Finn, and successfully steals Marceline's axe bass. Finn and Marceline give chase.
Marceline's father moves throughout Ooo, consuming the souls of all living creatures that he can find. Finn and Marceline first try to crush him with a rock, but the resulting skirmish between father and daughter merely infuriates Hunson Abadeer. He assumes that Marceline is trying to kill him to take over the Nightosphere, but she merely wants her bass guitar back.
Finn and Marceline attempt one last time to stop Hunson Abadeer, who has now grown huge. Due to his size, Finn is easily defeated. Marceline, infuriated by her father's lack of understanding, storms off. Finn, in a last-ditch effort to save the day, plays back the recording of "The Fry Song". Suddenly, Marceline's father understands why she is upset, and the two reconnect. Finn uses this beat as an opportunity to cut all of the souls free from Hunson Abadeer's "soul sack", and banishes him back to the Nightosphere.