Sever the Hedron Links — Main Quest Walkthrough

Objectives

Reach the Unknown
Progress Pope's Research Side Mission
Sever the Link Near the Patterned Evac Building
Sever the Link Near the Patterned Field Office

Walkthrough step-by-step

Reach the Unknown

After the first Hedron Link was destroyed, two more slammed into the Patterned city above the Oldest House. Dylan will disrupt the Pattern and sever both — then go after the Hedron itself.

To return to the Unknown zone, first go back inside the Oldest House: take the elevator on the floor above Pope and choose Roof Access, which takes you back to where you entered the Unknown previously. Activate the Oldest House Rooftop fast travel door down to the left so you can return without using the elevator.

Progress Pope's Research Side Mission

Once in the Unknown, you must progress the Pope's Research side mission to reach the main part of the area and the two Hedron Link sites. It works like this: find the balloons and cut them down to reveal a crate, break the crate with an attack to reveal probes, then place the probes in the red circles near the balloon. Probe placement spots appear on the minimap (top right) and beep as you get close to the correct spot. They must be placed in the correct order, after which a Gravity Well appears that carries you to the next island.

All the Unknown islands connect through these balloons and Gravity Wells — there is one Pope's Research objective on each island (two on the big Central island). See the Pope's Research walkthrough for the details.

Sever the Link Near the Patterned Evac Building

Once you reach the south island with the path leading to the Evac Building, find the spot where you can see the platforms leading to the island the link goes to. Jump across and interact with the TV. Inside is the Hedron Factor boss.

The Hedron Factor spawns single heavy enemies one at a time that you must defeat. After each set of two, when the health bar reaches the blue dot, you must defeat a group of weaker enemies while avoiding the mines it periodically drops on the ground. Once heavy enemies start spawning again, focus them down, and repeat the pattern until the boss is defeated.

Sever the Link Near the Patterned Field Office

Once you reach the northeast island with the path back to the Oldest House, find the spot where you can see the platforms leading up to the island the link goes to. Jump across and interact with the TV. Inside is the Hedron Proxy boss.

The Hedron Proxy is made of heavy brick enemies and sends them out from the main body to attack — wait for them to charge, dodge out of the way, then attack them to deal damage. During the final few heavy enemies, it also begins spawning groups of small ground enemies, which you must watch for while tracking the large ones. Defeating both bosses, in either order, completes the mission.