Perfection is a Special medal featured in Halo 3, it can be gained by winning a game of Slayer with a minimum of 15 kills in a row without dieing. If the Slayer game was a Team Game, you will have to achieve those 15 kills alone and your team must win. The concept to get those 15 kills is to avoid being seen as much as possible, camping and sniping is highly recommended for a perfect 15 kills.
Save This Film is an Achievment related to this Medal. You need to earn this medal in a matchmaking game on any of the mythic maps to earn this achievment. This is possibly the hardest achievment in the game.
Related Threadswill this the first perfect scored xbox exclusive? - last post by @ Sep 14, 2010
Review from IGN: 9.5/10 Perfection (No spoilers) - last post by @ Sep 24, 2007
The close-to-perfect Halo 2 - last post by @ Dec 6, 2004
Halo 2 scores a perfect 10 - last post by @ Nov 4, 2004
Score Attack: Perfect Match? - last post by @ Jun 8, 2011