Rock Band 4 debuted in October, and developer Harmonix spent more than six months after the launch adding features new and old to the game in free updates. Now, the studio and co-publisher Performance Designed Products are set to release Rock Band Rivals, which will be the game’s first paid expansion when it arrives this October. Harmonix announced Rivals last month during E3, but didn’t provide any details on what the $29.99 expansion would contain.

Source: Yahoo Music
Link: Rock Band 4's expansion mixes This is Spinal Tap with VH1's Behind the Music