Today at the Rocket League Championship Series Live Finals, Psyonix announced a new mode coming in September: Rocket League Rumble.
According to the official blog, the new mode is a battle royale with random power-ups. It will sport 11 power-ups in all, with effects ranging from freezing the ball in-place, upping your impact power, or swapping positions with an opponent. The biggest effect seems to be the "Tornado," which sweeps up the ball and all your opposing cars into a funnel cloud.
Rumble will be available in online playlists along with private and exhibition matches when it launches sometime next month. Check out the trailer below.