History of Flame Refraction

Overview

Flame Refraction is the exotic trait on the Prometheus Lens, a Trace Rifle. Each kill returns part of the ammo spent to the magazine, which extends the beam's duration.

Ammo source

Most guides, including ProGameTalk, describe the returned ammo as coming from reserves. Some reports say it is generated instead, and the sources disagree on this point. Bungie nerfed the Prometheus Lens in a December 2017 update, but the sources do not detail how that changed Flame Refraction.