.3J.01. Horizon: Investigate

Upon arriving at Horizon, you will encounter your first Collectors. Be aware that one of the Drones can be possessed by Harbinger, granting it Shields and Armor but no health. Killing Harbinger will cause it to possess another Drone. You can either focus on eliminating Drones before dealing with Harbinger, or target Harbinger during its possession animation, which lasts several seconds, allowing you to attack it directly.

You will eventually face Harbinger, but not immediately. Initially, you will fight several Collectors who use a harmful particle beam. Utilize the abundant cover (press the cover button to crouch behind walls or objects) provided by the colony's residences as you engage groups of 4-5 Collectors.

The map is linear, but items are often hidden within residence units. Clear each area of Collectors and proceed, as they typically fly in from above.

You will find frozen colonists and additional items before the next major fight. Collect the Collector Particle Beam, a laser weapon with ample ammo, good accuracy, no recoil, and no need for reloading. It is recommended to keep this weapon equipped until you acquire more Heavy Weapon upgrades.

Further exploration will lead you to the Collector General, Harbinger. Use the collector pods for cover, but be aware that Harbinger's missile-seeking weapon can dislodge you from cover if it detonates nearby. After clearing the area, search residences for items and bypass the door to continue.

Beyond the door, you will find an unfrozen human survivor. While speaking with them provides little information, you will receive a new objective: fix the defense tower targeting systems.