Complex sentence: In 1976, Butterfield performed at the Band's final concert, "The Last Waltz", accompanying the Band on the song "Mystery Train" and backing Muddy Waters on "Mannish Boy".
Split into simpler sentences: In 1976, Butterfield performed at The Band's final concert, "The Last Waltz". Together with the Band, he performed the song "Mystery Train" and backed Muddy Waters on "Mannish Boy".