The Call of Duty: Modern Warfare 4 beta begins this Friday, August 21, and everyone who takes part will have a chance to earn special rewards. As with previous Call of Duty betas, Activision is encouraging people to play by offering rewards for progressing through the ranks. The first reward, an emblem, is unlocked at level 4. The next, a charm, is unlocked at level 8, running all the way up to level 30.