Adventure Time (2010)

S2E1 It Came from the Nightosphere

After an unexpected incident, Finn and Marceline inadvertently set loose her malevolent father from the Nightosphere. He embarks on a chaotic spree, devouring souls and spreading terror. As chaos ensues, Marceline must confront her father’s dark legacy while teaming up with Finn to restore order and contain the threat he poses. Together, they navigate the challenges of their friendship and the shadows of Marceline’s past to stop him before it’s too late.