History of Terminus Horizon

Overview

Terminus Horizon is a legendary Arc Machine Gun (heavy ammo) with a High-Impact frame (360 RPM, 46 rounds) that favors accuracy while stationary. Listed perks include Triple Tap, Target Lock, Dragonfly and Voltshot.

Acquisition

Drops from the Spire of the Watcher dungeon (introduced in Season of the Seraph). Dropped by Ascend the Spire, Akelous and Persys. It is not listed as craftable or as having an Adept version in the sources checked. Per The Game Post and Kyber's Corner, the dungeon also drops the exotic Hierarchy of Needs.