From Halopedia, the Halo wiki
This article is about the Halo 4 achievement. For the Halo 4 level, see Composer (level); for the machine, see Composer.
Composer is an achievement in Halo 4. It is awarded to players for completing the seventh Campaign level, Composer, on any difficulty. The achievement is worth 10 Gamerpoints. It is represented by a shield with a "7" inside it.