Protector Sentinel (Trove)

These Protector Sentinels are a specialised variety of the Forerunner automatons Sentinels found on the shield world Trove, only manufactured in Protector plants.

Design details
Like Aggressor Sentinels but smaller in size, Protector Sentinels have two arm-like appendages and a central head resting above its center casing. A single appendage pointing downwards cover the undercarriage, the anti-gravity unit that propels the construct, and the different devices that provide the Protector with its support capabilities. Unlike other Sentinels, however, there are patterns of blue light running on the casing, much like Promethean constructs.

The offensive variant is differentiated from its defensive counterparts by its side appendages curving upwards and a more angular bottom appendage. It also features a laser targeting system that constantly scans the nearby area for threats. The defensive variants, Healing Protectors and the Shield Protectors, are identical in shape; Healing Protectors differs from Shield Protectors as they radiate a green aura akin to the aura found around a Forerunner Spire of Healing.

Serving a role in combat support, Protectors are programmed to follow a host, which could be a small group of soldiers or a single vehicle. Functionally, they are slightly weaker than Aggressors, both in durability and in damage output. Due to their specialised function, they appear less often in combat situations than Aggressors or Super Sentinels, both of which possess stronger combat capabilities.

Variants
There are three different variants of the Protector Sentinels, each with a specialised role.
 * The Offensive Protector is programmed to repel attackers with a pulse of laser fire.
 * The Healing Protector is programmed to heal wounded soldiers (likely with the same technology used by Forerunner Spire of Healing) or repair damaged vehicles when they are out of combat.
 * The Shield Protector is programmed to project a rechargeable dome-shaped energy shield around its host.

Gameplay
In Halo Wars, only Offensive Protectors make an appearance in the campaign level Escape. They do not attach to another Forerunner unit and only serve as a weaker version of the Aggressor.

In Skirmish, Protector Sentinels are available for players to purchase from the Protector plants on the Skirmish map Labyrinth. Like Aggressors, each Protector costs 1 population and 100 Supplies. Their special ability is to attach themselves to one of the player's other units, following it in action. Only one can be attached to a single unit one time. Once attached, a Protector cannot be removed unless destroyed.

Spartan and Regret uses
Unlike most units which are limited to only one Protector Sentinel, Spartans and the Prophet of Regret are able to receive multiple Protector Sentinels assigned to them due to their "special units" feature.


 * Prophet of Regret: Upgrading the Prophet of Regret with Ancestral Perversion will give him two Offensive Protectors for his personal protection.
 * Spartans: There are two methods of getting two Protectors assigned to a Spartan where the Spartan has to hijack a vehicle:
 * The Spartan and a friendly vehicle must each acquire a Protector. Ordering the Spartan to commandeer the vehicle will allow the vehicle to possess both Protectors. This only possible with friendly vehicles because an enemy vehicle's Protector will be destroyed in the hijacking process.
 * The Spartan must have an assigned Protector. The Spartan then hijacks an enemy vehicle or commandeer a friendly vehicle. After commandeering a vehicle, assign another Protector to the vehicle. If that vehicle is destroyed, the Spartan would still eject as normal, but will only keep the Protector that was assigned to them before commandeering a vehicle.

Wraith and Locust uses
Wraiths and Shua'ee-pattern LocustLocusts have the opportunity of multiple shields because they have shields and assigning a Shield Protector would give them a second one.
 * Wraiths: After upgrading Wraiths with Heavy Shield upgrade, a Shield Protector will grant the Wraith a second layer of energy shield.
 * Locusts: They have shields by default. It's very helpful for the Locust because they can still have a shield when they use the Overdrive ability.

Trivia

 * If a unit is being airlifted by the Transport power, the Protector unit will follow the Pelican, providing it with its capabilities. When the Pelican reaches its destination, the Protector would be reassigned to its original host.
 * The shield that the Shield Protectors give to assigned units protect them from being 'stunned' as well.
 * If the player attaches one of the other two Protectors to the Prophet of Regret before researching Ancestral Perversion, one of the Offensive Protectors will not appear when it is researched.

List of appearances

 * Halo Wars