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Ossoona was a Covenant Sangheili title and rank granted to certain individuals within Fleet Security. They were given active camouflage and sent on espionage missions. The term "Ossoona" translates to "Eye of the Prophet" in the Covenant language.
Unlike most other Covenant rankings, "Ossoona" was a temporary rank bestowed by the Prophets upon specially selected Sangheili warriors and is a subclass of the Stealth Sangheili rank. Ossoonas are roughly equivalent to expendable spies or assassins, sent on high-risk missions of critical importance.
Due to a lack of intelligence on the United Nations Space Command, the Prophets had begun to pull a handful of Sangheili from active duty into temporary service as Ossoonas. In order to be chosen, these individuals had to be experienced officers. This is because higher ranking Sangheili are more valuable in active duty, whereas the lower ranking Minors were considered too inexperienced and liable to either become compromised or abandon their mission in pursuit of their own personal glory.
The mission of an Ossoona was to collect information on the enemy while avoiding any type of combat. Most Sangheili felt that there was little honor in such an assignment, but complied in accordance to their religious duty. Covenant leaders felt that zeal was a quality to be admired, but an espionage job would help tame young Sangheili and teach them the finer arts of stealth in battle.
The title of Ossoona was usually bestowed for a single mission, though a series of missions were sometimes given. An Ossoona would always be equipped with active camouflage generators and recording devices similar to UNSC helmet recorders. They were usually equipped with a Type-25 plasma pistol and Type-1 plasma grenades as well as energy shielding just in case they were to be discovered. Ossoona missions would tend to include non-combat intelligence gathering, such as capturing high ranking enemy personnel, equipment, AIs, weapons, etc.
Because many Sangheili were reckless and tended to destroy everything in their path, the Prophets (hoping to learn more about the humans, including the location of Earth) sent 'Nosolee on a special mission to gather intelligence. Even though he was killed when Captain Keyes shot him in the head with an M6D magnum, the attendance of the Ossoona in the life pod Captain Keyes had fled aboard alerted the Covenant to his importance, and ensured that they captured him instead of killing him along with his party.
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