SEKRIT ENCORE!!!!!
Marceline will invite the other two bands on the stage to perform another set together, if they're up for it. If not? Whatever, she's happy to play for whoever wants to hear it.
"Francis Forever" is usually her go-to Battle of the Band song, but she went more emotional for the competition. It's totally worthy of an encore. (If you want to hear Marceline's voice actress sing the entire song, it's the second song in this medley 50 seconds in.)
"The Fry Song" by request. She has friends of Baelfire's to impress, yo.
And of course, she'll back up anyone else's songs they wanna add.