Joshua Luellen got his start, like much of Atlanta hip-hop's new school, with Gucci Mane's 1017 Brick Squad, making suitably aggressive beats for Waka Flocka Flame. As head of the 808 Mafia production team, Southside forged a signature sound out of rattling hi-hats and screaming sirens on tracks like Birdman's “Tapout”, leading to even bigger collabs with JAY Z and Drake.