Last year Yasiin Bey aka Mos Def, officially announced his retirement from the rap game. That huge announcement was followed by news of a final tour and the “last album” of his career, Dec. 99th. Now Mos Def has revealed plans for his very last live performance. Yasiin Bey is set to perform his final set at Atlanta’s ONE MusicFest which is scheduled to happen September 8 and September 9 .