Built from Scratch

Built from Scratch is the four-piece set bonus of Ferropotent, a Vanguard armor set. While your ammo reserves are low, weapon final blows against combatants add ammo progress based on the weapon's ammo type: primary weapons feed Special ammo progress and Special weapons feed Heavy ammo progress.

The bonus needs any four of the five Ferropotent pieces, which leaves the fifth slot free for an exotic. The set is earned by ranking up the Vanguard playlist and focusing at Zavala.