Invincible

Invincible is a Spree medal awarded in Halo 3 and Halo: Reach multiplayer awarded for killing 30 opponents in a row without dying, or, in Halo 3: ODST and Halo: Reach campaign and firefight, for killing 100 enemies in a row. It is represented by a blue target inside a black hexagon. In Halo 3 is the most difficult spree medal to achieve. In Halo 3 it is also known by some people as the hardest medal to achieve, competing with the Killionaire Medal and the Extermination Medal.

Trivia

 * This medal is usually achieved by playing Big Team Battle and killing people instead of actually trying to get the flag, bomb, etc.
 * Earning this medal in campaign or Firefight in Halo: Reach will unlock Jun-A266's helmet for the player's Xbox 360 avatar.
 * This medal in Halo: Reach is no longer the highest spree medal in the game, as there are 2 more spree medals: Inconceivable! and Unfrigginbelievable!