Unidentified Prophet (Heian)
From Halopedia, the Halo wiki
Prior to a visit to Heian, a world under Covenant control, a Human team, comprised of three Orbital Drop Shock Troopers led by SPARTAN-II Cal-141, managed to slip past Covenant army patrols and take up an overwatch position above a landing zone in a staging area.
Just before the SPARTAN was able to shoot the Prophet after his arrival in a Type-52 Phantom, a Jiralhanae Chieftain snuck up on the team and injured the veteran sniper. During which, Cal ordered O'Brien to take the shot. After sighting in on the unsuspecting Prophet, O'Brien managed to kill the alien from a distance of two miles. Upon the Propet's death, his Jiralhanae bodyguard cried out in great emotional distress at the loss of his leader and shame in failing to protect him.
His death allowed for the United Nations Space Command to regroup and exploit the new weakness in the Covenant supply chain.
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