Complex sentence: Later, the Bellas are invited to an exclusive riff-off against DSM, also in attendance are the Treblemakers, the Tone Hangers (a group of former Treblemakers, including Bumper), and the Green Bay Packers.
Split into simpler sentences: Later, the Bellas are invited to an exclusive riff-off against DSM. Also in attendance are the Treblemakers, the Tone Hangers (a group of former Treblemakers, including Bumper), and the Green Bay Packers.