Extermination

Extermination is a special medal awarded in Halo 3 Multiplayer for getting at least an overkill on the opposing team that results in all the team being dead. It is represented by a gray cross with a red skull. This medal is only awarded if the entire opposing team is exterminated.

This medal is extremely hard to get on purpose as you rarely find all of the same team together, and it is hard to stay alive killing at least four enemies within four seconds, each within those four seconds. This is most commonly received on Team SWAT, as you only have to get headshots, there is also a possibility of obtaining this in Grifball. Another easy way to get this is having the Rocket Launcher (or any other explosive weapon) and hope the other team is near each other in Ranked Team Slayer game, due to their being four opponents, not five like in Social Slayer, but sometimes by luck using the Spartan Laser is also another way.