Pendleton Ward Nightmare Rainicorn, Shelby, Nerdy Alien Voice, Old Man Rainicorn Creator, Guest Voice, Writer Jeremy Shada Finn Voice John DiMaggio Jake Voice Hynden Walch Princess Bubblegum Voice Tom Kenny The Ice King Voice Niki Yang Lady Rainicorn Guest Voice Vincenzo Rauso Tiffany Guest Voice Steve Little Hair Guy Guest Voice Dee Bradley Baker Baby Finn, Bug Child, Marauder 6 Guest Voice Matt L. Jones Mountain Man, Marauder 5, Electroid Guest Voice Tom Wilson Head Marauder, Cat Man, Coal Guy Guest Voice Maria Bamford Squid, Bug Mom, Margaret Guest Voice Kent Osborne Toad, Joshua Guest Voice, Writer Fred Seibert Executive Producer Kelly Crews Producer Larry Leichliter Director Sean Jimenez Writer Bert Youn Writer