Campaign Complete: Legendary (Halo 3 achievement)
From Halopedia, the Halo wiki
Campaign Complete: Legendary is a Halo 3 Campaign Achievement. It is earned when the player completes the Halo 3 Campaign on Legendary difficulty. This Achievement gives 125 Gamerpoints to the player and unlocks the Campaign Complete: Normal and Campaign Complete: Heroic achievements if not yet earned.
It is represented by a shield with two crossed Combat Knives. On top of this is a cracked Elite skull, which forms the Legendary difficulty symbol.
The achievement is still awarded when playing Co-op online and offline. If another player hasn't completed Heroic yet but helps complete Legendary on only a few missions they will still get the Achievement.
It is also recommended that when playing on Legendary you play on Co-op.
This Achievement unlocks the EOD Spartan Armor Helmet (The shoulders and chest plate are unlocked by completing specific levels on legendary, as opposed to the entire campaign).
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