Cleansing (achievement)
From Halopedia, the Halo wiki
Cleansing
Cleansing is an Halo 3 Achievement.
It is earned when someone finishes the Campaign mission Floodgate on the Normal, Heroic, or Legendary difficulties, and gives 30 Gamerpoints to the player.
This Achievement is represented by a blue plate, with a roman numeral V (five) on it.
The level must be played from Mission Start in order to unlock the achievement. Playing in co-op will still earn the achievement.
See also