This page of the guide contains details about the Reunion mission in Outriders. Here you will find a detailed walkthrough of the entire mission. Reunion is the fourth mission in Outriders. You will have to make your way to the solar tower.
At first, you will face a series of fights in the room from the photo above. Once the gate is opened, enemies will appear in the back. In the same room, near the unlocked entrance, there is a small room with a chest - it contains items. Just outside the gate you will find another chest. After that, follow the mission objective and then meet Jacob and Shira at the base.
Go to the solar tower and defeat Gauss
Traveling to the solar tower will require breaking through to a separate location. Along the way, you will encounter quite a few enemies in several places.
You will also encounter an elite enemy on your way to the tower - this will be the type of enemy that will rather fight at close range. Try to look around the location, you will find some equipment crates as well as minerals. At the very end, you will face your first stronger enemy - Gauss.
You can find out how to fight the boss on the Gauss page
After defeating the opponent, go back to the base, talk to Shira, and then go to Jacob and proceed to the new location.