Still no closer to understanding what Project Zero Dawn is after exploring the Grave-Hoard, Sylens informs Aloy that their next stop lies buried beneath Sunfall, the Shadow Carja capital. Knowing that Aloy will not be able to approach the capital safely while Eclipse agents equipped with Focuses roam the city, Sylens formulates a plan to take down the Eclipse's Focus network. He instructs Aloy to meet him at the location marked on her Focus, at the falls southeast of Brightmarket.
Closing in on the location, Sylens informs Aloy that upon close inspection of the rock wall, she will find handholds that will take her up. Scaling the wall, Aloy comes to a campsite in an a small alcove where she rests until nightfall to await further instruction. When nightfall comes, Sylens reveals that he has brought Aloy to the Eclipse's main base where she will be able to disable the Focus network. He explains that her target is a derelict Tallneck whom the Eclipse have modified to function as a kind of router for their network. Thus she is to infiltrate the base and destroy the transmitter atop the Tallneck's head. Upon her questioning, Sylens admits that he used to assist the Eclipse but departs before Aloy can inquire any further.
Squeezing through the crevice, Aloy emerges into a clearing patrolled by a number of Corrupted machines, at the back of the base. Sneaking past the machines, Aloy makes her way to a ledge overlooking the camp where a number of cultists are prowling. Despite Sylens' intel, Aloy only comes across the legs of the Tallneck. Concluding it must have been moved, Sylens then instructs her to check the ravine to the left. Either by sneaking past or killing the cultists, Aloy comes across a tent; after listening to the numerous datapoints scattered around the tent and examining the ceremonial armor on display, she realizes that it belongs to Helis.
Moving on, Aloy fells a tree to cross the ravine where she finds the Tallneck, surrounded by a series of wooden platforms, although deserted. Climbing to the top, Aloy sees the skeleton a Metal Devil which she deduces must be HADES. As she tries to pry the casing off the module atop the Tallneck's head, she is shocked and thrown back, with HADES using the wire connecting the machines to approach Aloy. While knowing she cannot destroy HADES then, she drives her spear through the module, successfully crashing the Focus network. At this, HADES orders Aloy to be killed, with a Deathbringer shooting down the Tallneck. Now under heavy fire, Aloy flees, heading for the rappel point by the bridge. As she throws herself over the edge, the bridge is blown up, severing Aloy's tie to the rappel point and sending her plummeting into the river below. Injured although not pursued, Aloy climbs to the riverbank where Sylens appears once again. Angered that he led her to HADES but knowing that she needs her Focus, she makes her way to the Shadow Carja capital to find the answers that both she and Sylens seek.
- Hunt down the Proving killers (if Revenge of the Nora has not been completed)
- Go to the Campfire and speak to Sylens (if Revenge of the Nora has not been completed)
- Go to the Location that Sylens indicated
- Climb the Escarpment
- Rest at the Campfire
- Infiltrate the Eclipse Base
- Search for the derelict Tallneck
- Crash the Eclipse Focus Network
- Escape the Eclipse Base!