In Killzone 3, in multiplayer, get a 5 kill streak, while playing in the Blood Gracht. Blood Gracht is only available in Guerrilla Warfare matches. You can set Blood Gracht as your preferred map for Guerrilla Warfare in the Main Multiplayer menu. Your will need to achieve 5 kills without dying in this map. This map is very small so there plenty of chances to get cheap kills with grenades and Proximity Mines.