The Unfrigginbelievable medal is awarded to players after killing 40 opponents in a row without dying in multiplayer and Halo 4 Spartan Ops or after killing 1000 opponents in a row without dying in Firefight or Campaign in Halo: Reach. It is the final of the spree medals and one of the legendary medals in Halo: Reach and Halo 4. This medal can be awarded in any gametype as long as the kill limit is above 40.
- This medal has the same appearance as the Halo 3 Invincible medal.
- The highest spree possible is 255 kills. Even if you get more kills after that number without dying, it will still say that your highest spree was 255 kills. This is most likely because 255 is the maximum value representable by an eight-digit binary number and therefore the maximum representable by an unsigned 8-bit byte.
- This limitation is seen throughout the world of gaming. One of the more commonly known instances of this is the 256th stage of Pac-Man where a kill screen makes the level impossible to complete.