Z-510 focus turret
From Halopedia, the Halo wiki
The Z-510 beam turrets are turrets of a similar nature to those located on Trove, but smaller in scale. They are typically constructed by Watchers and possess a deadly, long range beam weapon, akin to a Sentinel Beam. The Focus Turret was manufactured and developed by Ferrarius Assembler Vats. When destroyed, Forerunner beam turrets disintegrate in a manner resembling that of Promethean Knights.
During the Battle of Draetheus V, Merg Vol was able to activate the turrets around the control room for X50's primary weapon after having spent considerable resources to unlock its secrets. The turrets aided Vol in battle against Spartan Sarah Palmer alongside his forces. However, Merg Vol was ultimately defeated and killed by Palmer. When accessing the Cistern, Palmer encountered beam turrets guarding two of the three power cores she had to destroy in order to unlock the main door. Several more protected the area of the Cistern where Spartan Edward Davis' remains were being held in a Durance, particularly the power cores Palmer had to destroy in order for a Pelican to extract the Durance.
In July 2557, John-117, and later the crew of the UNSC Infinity, faced several such turrets inside the shield world Requiem. Later, a number of these turrets were hacked by Cortana on the Mantle's Approach during the Didact's attack on Earth, during which time they took on a blue light, like those of the Sentinels on Requiem, as opposed to the characteristic orange coloration of those under the Didact's control. The turrets temporarily repelled waves of Crawlers to help John-117 on his way to destroy the Composer.
When the Infinity returned to Requiem in 2558, several beam turrets were again used against UNSC forces. Fireteam Crimson faced numerous turrets during their missions. At some point, the Spartan-IVs were able to turn the turrets of the location "Control" into allies to help repel members of Jul 'Mdama's Covenant. Later, when the Spartans searched for Dr. Halsey's signal at Cyclone, the Librarian provided them support with some allied beam turrets along with Aggressor Sentinels.
After Cortana took over the Promethean forces, focus turrets took on a modified design. Larger anti-vehicle turrets were encountered on Meridian by Fireteam Osiris, being more heavily armed but rarer overall. The Warden Eternal would also use focus turrets as support in his engagements against Osiris and Blue Team on Genesis. Later, Osiris encountered more focus turrets in their mission to free Blue Team from Cortana. In Warzone simulations, like those on March on Stormbreak, should the Warden Eternal be encountered as a Mythic boss, he may also spawn focus turrets against the two Spartan teams who are competing against each other for victory in the simulation.
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