The Invincible Medal is a medal that you gain for killing opponents in a spree and considered one of the most toughest medal to gain. In Halo 3 and Halo: Reach Multiplayer, you can get this medal by killing 30 opponents in a row without dieing. On the other hand, it takes 100 kills in a row to get this in Halo 3: ODST.
You might easily get this medal by trying to compete with beginners or people who sucks at it.
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