Invincible

Invincible is a Spree medal awarded in Halo 3 Multiplayer for killing 30 opponents in a row without dying. Due to its very rare nature, the medal is not displayed in Ranked statistics on Bungie's website, although it is displayed in Social statistics. It is represented by a blue target inside a black hexagon. It is the hardest Spree medal to achieve. This Spree medal is actually shown in the "special" medals row, instead of the "spree" medal row.

For an example of this medal being reached, follow this link, and download the file called INVINCIBLE to your xbox, to play back through Halo 3.

An example of the INVINCIBLE medal availiable here