Last night, Kanye West was the headliner of Hot 107.9's 20th Birthday Bash in Atlanta, GA. The set included a couple surprises, including an appearance from 2 Chainz during "Mercy" and a freestyle that referenced the recent murders in Charleston, South Carolina. While he was in Atlanta, West also hung out with OutKast at the Waffle House. He also reportedly spent some time in the studio with 2 Chainz. Check out the freestyle after the jump.