Editing Retriever Sentinel

{{Status|Canon}}
{{Disambig header|a variant of [[Strato-Sentinel]]s|the other variant|Steward Sentinel}}
{{Forerunner infobox
|name=Retriever Sentinel
|image=[[File:Enc22 RetrieverSentinel.png|300px]]
|role=Construction and mining{{Ref/Book|Id=EVG|EVG|Page=167}}
|length={{Convert|1587.9|ft|m|disp=flip|sp=us}}{{Ref/Reuse|Enc22}}
|width={{Convert|1503.6|ft|m|disp=flip|sp=us}}{{Ref/Book|Id=Enc22|Enc22|Page=329}}
|height={{Convert|387.5|ft|m|disp=flip|sp=us}}{{Ref/Reuse|Enc22}}
|mass=
|propulsion = [[Impulse drive]]{{Ref/Reuse|Enc22}}
|armament=
*Sterilization beam{{Ref/Reuse|Enc22}}
|armor=
|shields=Little to no [[energy shielding]]{{Ref/Reuse|HITD6}}
|systems=
*Gravitic impeller{{Ref/Reuse|Enc22}}{{Ref/Reuse|HITD6}}
*Reconstitution emitters{{Ref/Reuse|Enc22}}
}}
{{Quote|It's a Strato-Sentinel. It's one of the automated drones the Forerunners use on their artificial worlds. The Covenant originally thought them to be holy warriors of the Sacred Rings. There are many types of Sentinels that the Forerunners created—this particular one is designated as a Retriever.|[[Usze 'Taham]]{{Ref/Novel|Id=HITD6|HiTD|Chapter=6}}}}
The '''Retriever Sentinel''', is a variant of [[Strato-Sentinel|Strato-]][[Sentinel]] drones employed by the [[Forerunner]]s. Considered to be one of the more powerful variants of the Sentinel, Retrievers are massive, ship-sized drones that were utilized to construct installations of the [[Halo Array]] from [[Installation 00]], as well as to provide maintenance to the Ark itself.{{Ref/Game|Id=pl retriever|HW2|Phoenix Log|Detail=Retriever Sentinel}}

==Overview==
===Design details===
[[File:Archaeology.png|thumb|250px|left|[[Nathaniel Palmer]] and other scientists observe Retrievers operate on the Ark.]]
{{Quote|Our records indicate that it employs an artificially produced gravitic force to remove minerals from a planet's surface. Those minerals in turn are used to build Forerunner structures and installations.|Usze 'Taham, referring to the Retriever Sentinels{{Ref/Reuse|HITD6}}}}
A Retriever is capable of producing an [[Artificial gravity|artificial gravitic force]] that allows it to remove materials from a world's surface. Once in position above an acceptable place to harvest, the Retriever deploys its blue, gravitic beam towards the world's surface and begins hauling chunks of land caught in the beam into its underbelly.{{Ref/Reuse|HITD6}} The mining process utilized by a Retriever is noted to create a tornado-like effect as the ground is pulled into the Sentinel's hold.{{Ref/Novel|Id=HITD15|HiTD|Chapter=15}} If deemed necessary, a Retriever is capable of connecting and merging with another Retriever and forming a single unit. Combined Retrievers somewhat resemble an average Retriever, though they seem to be more effective in combat and are significantly more maneuverable. With no apparent drawbacks, a combined Retriever seems to take on the benefits of both Retrievers' speed and weaponry.{{Ref/Novel|Id=HITD7|HiTD|Chapter=7}}{{Ref/Novel|Id=HITD18|HiTD|Chapter=18}}

When a Retriever is threatened or attacked, these Sentinels may use their gravitic beam as a dangerous and highly destructive,{{Ref/Game|Id=pl sentinel|HW2|Phoenix Log|Detail=Forerunner Sentinels}} though cumbersome, weapon. As the Sentinel was not designed for combat situations, Retrievers have little to no shielding.{{Ref/Reuse|HITD6}} In [[2555]], [[monitor]] [[000 Tragic Solitude]] outfitted thousands of Retrievers with massive energy weapons mounted on their fronts. These weapons are similar in design to the [[Sentinel beam]]s employed by the smaller [[Aggressor Sentinel]]s.{{Ref/Reuse|pl retriever}} These Retrievers were capable of utilized powerful volleys of energy against opponents and were significantly faster and had greater maneuverability in space.{{Ref/Reuse|HITD7}}

===Role===
{{Quote|I thought Retrievers were just for mining and gathering minerals!|[[Captain]] [[Annabelle Richards]], upon seeing a heavily armed Retriever{{Ref/Reuse|HITD7}}}}
The Retrievers are among the most powerful of the Sentinels employed by the Forerunners,{{Ref/Reuse|pl retriever}} with their primary purpose being the mining, gathering, and transporting of minerals and other natural resources from a world.{{Ref/Reuse|HITD7}} Using its artificially created gravitic force, Retrievers extract materials from a world's surface and transport to construct Forerunner structures and installations.{{Ref/Reuse|HITD6}}{{Ref/Reuse|Enc22}}

The Forerunners utilized Retrievers to help in the maintenance of Installation 00.{{Ref/Reuse|pl retriever}} The Retrievers employed at the Ark worked with [[Assembler Sentinel]]s to construct new installations. Populating the [[Foundry (location)|Foundry]],{{Ref/Reuse|pl sentinel}} Retrievers mined and gathered raw materials from the planetoid hosted in Installation 00's center and transported them to a forge within the Foundry that refined, processed, and stabilized the materials into the mold of a Halo installation.{{Ref/Reuse|HITD15}} The Assemblers would then use these resources to build components of the installations.{{Ref/Game|Id=pl foundry|HW2|Phoenix Log|Detail=The Foundry}} Although usually automated, Retrievers can be controlled by a monitor. Monitors are capable of effectively utilizing Retrievers in combat, and can have them overwhelm opponents.{{Ref/Reuse|HITD7}}

A Retriever is programmed to complete its tasks with no deviations or hesitations.{{Ref/Reuse|HITD18}} Although the function of the Retriever is primarily construction-related, the Sentinel is able to defend itself, or its installation, if necessary.{{Ref/Reuse|pl sentinel}} However, Retrievers maneuver poorly and are unable to effectively combat modern [[Sangheili]] and [[human]] vessels alone.{{Ref/Reuse|HITD7}} Thus, Aggressor and [[Protector Sentinel]]s are primarily used as defensive constructs on installations.{{Ref/Reuse|pl sentinel}}

===Variants===
Multiple variants of Retriever have been seen in use across Forerunner megastructures.
<gallery class="center">
File:HW2 Retriever.png|The Retriever variant found on [[Installation 00]].{{Ref/Reuse|pl retriever}}
File:Enc22 RetrieverSentinel.png|Another variant of Retriever.{{Ref/Reuse|Enc22}}
</gallery>

==Operational history==
===Prehistory===
Retriever Sentinels were utilized by the [[Forerunner]]s to aid in the construction of the [[Halo Array]] at [[Installation 00]], with the intentions of firing the rings to wipe out the [[Flood]].{{Ref/Reuse|pl retriever}} 

===Conflict on the Ark===
After the [[Battle of Installation 04|destruction]] of [[Installation 04]] on [[2552#September|September 23, 2552]], Retrievers on Installation 00 began to mine the planetoid captured in the Ark's Foundry to construct [[Installation 08|a replacement installation]]. On [[2552#December|December 11, 2552]], these Retrievers were encountered and observed by [[Sangheili]] and [[United Nations Space Command]] forces during the [[Battle of Installation 00]].{{Ref/Reuse|HITD6}} The battle ultimately resulted in the Ark becoming heavily damaged, leading to 000 Tragic Solitude—Installation 00's now-[[Rampancy|rampant]] monitor—allocating all of his time and resources to the construction of thousands of heavily armed Retrievers that would mine [[human colonies]] for resources to repair the Ark, blaming humanity for damaging his installation.{{Ref/Novel|Id=HITD12|HiTD|Chapter=12}}{{Ref/Novel|Id=HITD13|HiTD|Chapter=13}}{{Ref/Novel|Id=HITD14|HiTD|Chapter=14}}

In [[2555#March|March of 2555]], Tragic Solitude used [[Bobby Kodiak|a captured human]] to initiate the activation of the Halo Array. As expected by the [[ancilla]], the United Nations Space Command and [[Swords of Sanghelios]] reopened the [[Excession]] on Earth to reach the Ark. With the portal now open, Tragic Solitude sent a Retriever through the portal to gather Earth's resources to repair Installation 00, which sustained heavy damages in the aforementioned battle. As the Retriever began to strip mine the country of Kenya, the [[cruiser]] {{UNSCShip|Endeavor}} immediately responded by attacking the Sentinel. With the aid of several UNSC attack craft, ''Endeavor'' was able to destroy the Retriever. As the UNSC and Sangheili team prepared to venture into the [[slipspace portal]] aboard ''[[Mayhem]]'', another Retriever suddenly exited—this time, heavily armed. However, the Sentinel was easily outmatched by ''Mayhem'' and was destroyed.{{Ref/Reuse|HITD6}} When ''Mayhem'' entered the [[intergalactic space]] around the Ark, dozens of Retrievers attacked the [[Ceudar-pattern heavy corvette|corvette]] and managed to down the ship.{{Ref/Reuse|HITD7}}

After the crew of ''Mayhem'' [[Operation: FAR STORM|succeeded]] in averting the activation sequence of the Halo rings, Tragic Solitude sent his army of thousands of heavily armed Retrievers through the portal to Earth. Though the [[Huragok]] [[Drifts Randomly]] managed to seize control of the Ark from Tragic Solitude, the monitor kept the Retrievers under his personal control, keeping Drifts from stopping their deployment. The Retrievers exited the portal over Kenya and some proceeded to extract materials from Earth, while others immediately [[Battle of Earth (2555)|engaged]] the dozens of vessels from the [[UNSC Home Fleet]] that were awaiting outside the portal. While the Retrievers' lack of armor made them vulnerable to human fire, their vast numbers overwhelmed the Home Fleet. However, members of the crew of ''Mayhem'' fired into the data banks of Tragic Solitude and the monitor reluctantly called off the Retrievers to convince his attackers to stop. The Retrievers retreated back into the portal and returned to the Ark, upon receiving Tragic Solitude's signal.{{Ref/Reuse|HITD18}} After Solitude's subsequent destruction, the thousands of Retrievers turned dormant, remaining adrift in the space around the installation without any monitor to guide them.{{Ref/Novel|Id=HITD19|HiTD|Chapter=19}}

===Human appropriation===
[[File:HW2 - Anders with Sentinels.jpg|thumb|250px|Retrievers under the control of Ellen Anders.]]
{{Quote|When we first arrived here, the Ark had suffered great wounds from our war against the Covenant, and so we activated dormant Retriever Sentinels and deployed them to strip-mine lifeless planets for the materials needed to repair the installation. Like watching a sleeping giant nudged into wakefulness, the reconstruction slowly reached full automation until we were no longer needed to guide the Sentinels and could simply sit back and record the wonder of a world being reborn.|[[Nathaniel Palmer|Nathaniel J. Palmer]], an archaeologist of Henry Lamb Research Outpost{{Ref/Game|Id=old wounds|HW2|Phoenix Logs|Detail=The Healing of Old Wounds I}}}}
Doctor [[Luther Mann]] theorized that the dormant Retrievers could be reactivated and utilized to repair the Ark, opening slipspace portals to strip-mine uninhabited planets for the resources and minerals required to repair the Ark.{{Ref/Reuse|HITD19}} In [[2557]], a human research team traveled to Installation 00 aboard ''[[Eden Rising]]'' to establish a permanent base on the Ark, the [[Henry Lamb Research Outpost]]. Desiring to repair the installation, the researchers activated the dormant Retrievers,{{Ref/Game|Id=pl henry lamb|HW2|Phoenix Logs|Detail=Henry Lamb Research Post}} under the guide and direction of the [[smart AI]] [[Isabel]]. To gain resources, the Retrievers were deployed to strip-mine lifeless planets. Before long, the Retrievers were able to enact repairs unsupervised,{{Ref/Reuse|old wounds}} leading to Isabel and the researchers setting to the task of cataloging and analyzing the installation.{{Ref/Game|HW2|Phoenix Logs|Detail=Isabel}} The Retrievers acted quickly and within months had largely restored the Ark to its former state,{{Ref/Reuse|pl retriever}} as well as constructing another [[Installation 09|replacement Halo installation]] at the Foundry.{{Ref/Level|HW2|From the Deep}}

However, in [[2558#October|October 2558]], the portal to the Ark had shut down again with the [[Banished]] arriving at the installation in the following month. The human researchers were killed by the Banished, while the Retrievers sought to defend their installation from the hostile invaders who were attempting to appropriate the installation for their own purposes.{{Ref/Reuse|pl retriever}} In [[2559#March|March 2559]], {{UNSCShip|Spirit of Fire}} arrived over the Ark, where the ship's crew soon came into [[Second Ark Conflict|conflict]] with the Banished. During the resulting battle, UNSC forces managed to access the replacement Halo installation, having it depart the Ark's Foundry. In response, heightened automated security protocols were initiated and Retrievers were deployed to repel the invaders. While Banished and UNSC forces battled on the surface of the new Halo, a Retriever attacked forces from both sides. After UNSC forces managed to damage the Sentinel, the Retriever retreated for repairs. With UNSC forces taking control of three nearby [[Control Tower]]s, Professor [[Ellen Anders]] of ''Spirit of Fire'' soon found a way to manipulate the Ark's command codes and bypass directive locks, allowing her to take control of the Retriever. Anders was then able to use the Retriever's weapons to destroy the Banished shield generator blocking access to the Halo's [[Control Room (Installation 09)|Control Room]]{{Ref/Level|Id=The Halo|HW2|The Halo}}

Retriever Sentinels also played a role in guarding Forerunner starfighters. Several protected the entrance of a {{Class|Despair|fighter}} hangar, attacking UNSC and Banished forces indiscriminately. After the cloaking shield was shut off, a Retriever attacked the UNSC forces who ultimately managed to destroy the Retriever, allowing them to see what was behind the cloaking field.{{Ref/Level|Id=Gatecrashers|HW2|Section=Halo Wars 2: Operation: SPEARBREAKER|SectionLinkText=Operation: SPEARBREAKER|Gatecrashers}} With the Retriever gone, Major [[Elijah Vaughan]] and [[Sunray 1-1]] were able to destroy the starfighter before the Banished could launch it to destroy the {{UNSCShip|Spirit of Fire}}.{{Ref/Level|Id=Not on My Watch|HW2|Section=Halo Wars 2: Operation: SPEARBREAKER|SectionLinkText=Operation: SPEARBREAKER|Not on My Watch}}

===Second Ark Outbreak===
{{Main|Outbreak on Installation 00}}
Atriox later issued orders to [[Pavium]] and [[Voridus]] to salvage material from around [[High Charity]]'s crash site for their ongoing campaign against the humans, warning them not to go beyond the [[containment shield]]. Two Retriever Sentinels were dispatched to stop the Banished from reaching the crash site which the Banished forces were unable to counter. However, Voridus managed to shut down the Sentinel defense network using a nearby terminal, disabling all Sentinel operations and causing the Retrievers to be destroyed. Ignoring Atriox's orders, Voridus breached the containment shield, releasing the Flood, which spread uncontrollably due to the Sentinels being disabled by the defense network.{{Ref/Level|Id=What Could Go Wrong?|HW2|Section=Halo Wars 2: Awakening the Nightmare|SectionLinkText=Awakening the Nightmare|What Could Go Wrong?}}

With the [[Flood]] unleashed upon the Ark once again from High Charity's crash site, Voridus traveled into a nearby Forerunner archive and managed to reactivate the Sentinel defense network.{{Ref/Level|Id=The Archive|HW2|Section=Halo Wars 2: Awakening the Nightmare|SectionLinkText=Awakening the Nightmare|The Archive}} As the Banished battled a [[Proto-Gravemind]] that was in danger of evolving into a [[Gravemind]], it retreated to safety and refused to respond to Banished attacks, having grown too strong. As a result, Pavium and Voridus directed their troops to clear out a nearby Sentinel lock, summoning a Retriever. The combined fire of the Banished and the Retriever forced the Proto-Gravemind to expose its core and then finally destroyed the creature, allowing the Banished and the Sentinels to contain the Flood outbreak.{{Ref/Level|Id=Manifestation|HW2|Section=Halo Wars 2: Awakening the Nightmare|SectionLinkText=Awakening the Nightmare|Manifestation}}

==Gameplay==
===''Halo Wars 2''===
*'''Info:''' Summons a powerful controllable Retriever Sentinel. Super Unit and Ultimate Unit for Sentinels.
*'''Tier:''' 0
*'''Cost:''' {{HW2Pop|30}}, {{HW2Supplies|2,000}}, {{HW2Power|2,000}}
In ''[[Halo Wars 2]]'', the Retriever Sentinel is a Super Unit for Sentinels exclusive to [[Ellen Anders|Professor Anders]] that can only be built using a leader power. Unlike the [[G81 Condor]] or [[Barukaza Workshop Scarab]], there can only be one Retriever Sentinel used by the player at a time. If the player picks the Retriever Unit leader power, Anders is able to deploy two types of Super Unit, the G81 Condor and Retriever Sentinel. In gameplay information, Retrievers are labelled as an Ultimate Unit.

During the fight on [[Installation 09]] in the campaign, Anders is able to take control of a Retriever Sentinel that initially attacks both the UNSC and the Banished. In the campaign, the Retriever is indestructible after the player manages to damage it to 25% of its HP, forcing it to retreat and repairs. The player must avoid the Retriever until Anders can take control of it.{{Ref/Reuse|The Halo}}

During [[Halo Wars 2: Operation: SPEARBREAKER|Operation: SPEARBREAKER]], the Retriever Sentinel is equipped with energy shielding and can call in Sentinel Swarms to repair itself. The player must destroy the nearby [[Aggressor Sentinel]]s to dissipate the swarm and continue their attack.{{Ref/Reuse|Gatecrashers}}

During the ''[[Halo Wars 2: Awakening the Nightmare]]'' level [[What Could Go Wrong?]], two Retriever Sentinels are dispatched to stop Voridus' Scarab and are dispatched once Voridus shuts down the Sentinel defense network at [[High Charity]]'s crash site.{{Ref/Reuse|What Could Go Wrong?}} In an attempt to destroy a [[Proto-Gravemind]] in the level [[Manifestation]], Pavium reactivates the Sentinel defense network and clears a Forerunner launch site, which summons a Retriever Sentinel. This Retriever Sentinel falls under the control of the player and plays a vital role as its firepower is needed to kill the Proto-Gravemind.{{Ref/Reuse|Manifestation}}

====Phoenix Log====
{| class="wikitable": style="margin-left: auto; margin-right: auto; border: none; width: 45%"
|+ '''[[Phoenix Logs|Phoenix Log]] - Retriever Sentinel'''
|-
|{{:Phoenix Logs/Forerunner/Retriever Sentinel}}
|}

==Gallery==
{{Linkbox|gallery=yes|gallerypage=Images of Retriever Sentinel}}
===Development images===
<gallery>
File:HW2 - retriever.png|Concept art of the Retriever Sentinel for ''[[Halo Wars 2]]''.
File:HW2-batlefield.jpg|Artwork of Retriever Sentinels, Protector Sentinels, and Aggressor Sentinels moving to attack [[Decimus]].
File:HW2 RetrieverWreckage.jpg|Artwork of Banished forces amidst the wreckage of a Retriever Sentinel.
File:HW2-Retriever_HiPoly.jpg|A high-poly render of the Retriever Sentinel asset.
File:HW2-PRD-Retriever_Front.png|A Retriever (Pre-release design) from the front.
File:HW2-PRD-Retriever_Back.png|A Retriever (Pre-release design) from behind.
File:HW2-PRD-Retriever_Ability.png|A Retriever (Pre-release design) charging its fusion bolt attack.
</gallery>

===Screenshots===
<gallery>
File:HW2-RetrieverSentinel2.png|A Retriever Sentinel in ''Halo Wars 2''.
File:HW2-Retrievercharge.png|A Retriever charging its fusion bolt attack.
File:HW2-Retriever&Protectors.png|A Retriever with a swarm of [[Protector Sentinel (Installation 00)|Protector]] and [[Aggressor Sentinel]]s.
File:HW2-Sentinelpower.png|A Retriever and other Sentinels attack a Banished [[Banished outpost]].
File:HW2-Retriever.jpg|A Retriever Sentinel from the side.
File:HW2-DatRetriever.jpg|A Retriever from behind.
File:HW2-RetrieverSide.jpg|A Retriever from the other side.
</gallery>

==List of appearances==
*''[[Halo: Hunters in the Dark]]'' {{1st}}
*''[[Halo Mythos]]'' {{Mo}}
*''[[Halo Wars 2]]''
*''[[Halo: Renegades]]'' {{Mo}}
*''[[Halo: Empty Throne]]'' {{Mo}}
*''[[Halo: Ascension on Atropos]]''

==Sources==
{{Ref/Sources|2}}

{{Forerunner|sentinel}}

[[Category:Sentinels]]