A Protector Plant is a type of Forerunner Sentinel Factory found in Halo Wars, but unlike the sentinel factory, it is smaller and can be used to purchase three types of Protectors, instead of standard sentinels and Super Sentinels. Each protector sentinel requires 100 resources to purchase and no tech level is required to purchase one instead of the sentinels and super sentinels. These protectors have the ability to attach themselves to a unit to give it support. The three types are Offensive, Healing, and Shield:
- "Shield" creates a shield, similar to a Bubble Shield in Halo 3.
- "Offensive" makes the Protector engage anything that attacks the units it's attached to.
- "Healing" heals the squad after combat, similar to the Medic for UNSC Marines.