From Halopedia, the Halo wiki
Followers is an upgrade only available at the Covenant Temple. Its icon is a picture of three Elites wielding energy swords. It also has a +10 symbol next to the picture, indicating how many extra units the upgrade offers. It requires 3 tech points which in the Covenant is called the Age of Reclamation. This upgrade costs 800 supplies.
- Increases Covenant army population to 50 rather than the original 40.
- Allows the player to build 2 Scarabs and make 3 Shua'ee-pattern Locust.
- Allows the player to outnumber and possibly outmatch your enemies.
- Enemies can also buy this upgrade.
- AI players use this to make up to two scarabs.
- The UNSC's counterpart upgrade to this, Reinforcements, is purchased at the Field Armory.
- Scarabs can be aided by Type-30 Locusts or any other Covenant if this upgrade is bought.
- This is one of the longest upgrades to obtain. Needing 3 tech levels and 800 supplies. By the time it is complete you won't have long before the enemy attacks you.