The Overkill medal in Halo 3, Halo 3: ODST, Halo: Reach, Halo 4, and Halo 5: Guardians is obtained by killing 4 opponents within 4 seconds of each other. It is available in all Multiplayer gametypes and has a Bungie difficulty rating of 7 (out of 10). It is represented by a bronze circle with 4 green stars.