Invincible

Invincible is a Spree medal awarded in Halo 3, Halo 3: ODST and Halo Reach Multiplayer for killing 30 opponents in a row without dying, or, in Halo 3: ODST, for getting 100 kills in a row. Bungie recently started showing the medal in Ranked Stats, since it has been occurring a little more often than they predicted.

This medal is usually achieved by playing Big Team Battle and killing people instead of actually trying to get the flag, bomb, etc. It is represented by a blue target inside a black hexagon. It is the most difficult Spree medal to achieve. It is also known by some people as the hardest medal to achieve, competing with the Killionaire Medal and the Extermination Medal. Needless to say, this is a very difficult medal to obtain, unless opponents who are killed by the player are particularly bad.