Units record · 7:35pm Mar 17th, 2019
Sentinel
Also known as an Aggressor Sentinel and by the Covenant as "Holy Warriors of the Sacred Rings, is a broad category of Forerunner-constructed robots designed to suppress Flood outbreaks, construct and maintain Forerunner structures, mine and retrieve raw materials, and protect Forerunner technologies from alien lifeforms. To this end, they possess limited artificial intelligence and boast a wide range of weaponry and equipment in the field
Sentinel manufacturing facility
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Constructor
Constructors are devices similar to Sentinels in design, that mainly repair damage to any Forerunner structure they can find, using weak energy beams similar to Sentinel Beams. The beams are small, blue, and are harmful if they come into contact with an organism. It is unknown whether they will harm the Constructor itself, though.
The Sentinels will come to their aid if they are attacked, as they are ill-suited for combat, having no weapon systems of their own; however, their beams will damage you if you get caught in the path.
Retriever
A Retriever also known as a Strato-Sentinel was a Forerunner Sentinel variant. Retrievers were designed to strip mine the resource moon located in the middle of Installation 00 using an artificial gravity beam to remove the materials from its surfac which are used to construct and repair various Forerunner installations.
They were designed to carry out terraforming projects and are capable of mining moons, asteroids and other planetary bodies. They are huge drones that were used to build installations of the Halodes Matrix of Facility 00, as well as to maintain the Ark itself.
Vanguard-class sentinel
Like most Forerunner constructions, the Vanguard-class sentinels have a long history. Originally used during the Forerunner-Flood war, they were created as a combat ship which could destroy super massive areas of infestation while not having an organic crew to be infected. Though in most cases they were largely successful thanks to their expendable nature and heavy firepower, they couldn't halt the Flood's conquest of the galaxy.
its size superior to a UNSC battle cruiser, and its firepower is the most destructive, when the covenant found a single unit, they sent a whole fleet to destroy a single unit, with serious losses.
You forgot the protector class from Halo Wars!