How to Unlock Eclipse Threads in Saros

TL;DR

• Eclipse Threads are a traversal ability that let you zip across large gaps along glowing energy lines.
• They unlock automatically in the Desecrated Fortress — the fifth biome in Saros.
• You must first defeat Legion, the boss of Biome 4 (Blighted Marsh), to reach Desecrated Fortress.
• Inside Desecrated Fortress, activate the Eclipse Device at a dead-end room, then pick up the glowing yellow item that appears.
• To use a thread, approach it and press L1. The Eclipse must be active for threads to work.
• Eclipse Threads are two-way — if one end doesn’t trigger, find and try the other end.
• Once unlocked, previously inaccessible areas in earlier biomes open up, including the Ancient Depths Nightmare Strand.

What Are Eclipse Threads in Saros?

If you have spent time exploring the early biomes of Saros, you have probably noticed faint glowing lines stretching across certain gaps. They look like beams of light or energy strands hanging in the air. There might be a container or an audio log on the other side, but no grapple point and no Jump Network Pad in sight. You can’t reach it — not yet.

Those lines are Eclipse Threads. They are a traversal tool that lets Arjun zip across large distances in an instant by riding along a fixed beam of light. Once you unlock the ability, they change how you move through every biome in the game.

Eclipse Threads are entirely static — they are set paths that always lead to the same destination. But where they lead is often worth following. Hidden rooms, audio logs, containers, and optional challenge areas all sit behind Eclipse Threads that were invisible to you in the early hours of the game.

When Do You Unlock Eclipse Threads?

Eclipse Threads unlock during the Desecrated Fortress, which is the fifth biome in Saros. Like every other permanent ability in the game, this unlock is tied directly to story progression. You cannot miss it, and there is no side quest or secret condition attached to it. Just keep playing and you will get there.

That said, you do need to clear a significant chunk of the game before the ability becomes available. Here is the full path to get there.

How to Unlock Eclipse Threads Step by Step

Step 1 – Progress Through the First Four Biomes

Before you can reach Desecrated Fortress, you need to work through the game’s first four biomes in order:

• Biome 1 – Shattered Rise: Defeat the Prophet. This unlocks the Jump Network and access to Ancient Depths. If you need help here, our guide on how to beat the Prophet in Shattered Rise covers the full fight.
• Biome 2 – Ancient Depths: Clear the subterranean tunnels and defeat Bastion.
• Biome 3 – Shattered Descent: Work through the vertical biome and defeat Rhabdom. This is also where you unlock the Grapple — our guide on how to unlock the Grapple in Saros covers that in full.
• Biome 4 – Blighted Marsh: Clear the marsh and defeat Legion, the fourth Overlord boss.

Step 2 – Defeat Legion in Blighted Marsh

Legion is the gate that blocks your path to Desecrated Fortress. Defeat it and a few story sequences play out back at the Passage. Legion is considered one of the more approachable bosses in the game, but it can still catch you off guard. Bringing a weapon with Auto-Hit is recommended — it helps track which of the flying enemies is the actual boss target and not a decoy.

Once Legion falls and the story scenes play out, use the World Dial at Primary to fast travel to the entrance of the Desecrated Fortress.

Step 3 – Reach the Eclipse Device in Desecrated Fortress

The Desecrated Fortress is a ruined citadel — large, open, and full of debris and falling structures. As you push through the biome, you will start finding Honorarium Sigils scattered around the rooms. Collect these as you go — they unlock the Sealed Chamber near the boss and are worth picking up.

Keep following the main path through the biome. After clearing several rooms, you will arrive at a chamber that appears to have no exit. There are no doors and no obvious way forward. In this room, you will find the Eclipse Device — the same alien-looking pedestal with hands surrounding a glowing ball that you have seen in every biome.

There is no path forward from here without activating it. Walk up to the device and hold Triangle to trigger the Eclipse.

Step 4 – Pick Up the Glowing Yellow Item

As soon as the Eclipse activates, a small glowing yellow item appears on the ground just ahead of you. Walk up to it and pick it up. A short dialogue plays — Arjun comments on the discovery — and the Eclipse Threads ability is permanently added to your kit.

That’s the full unlock. From this point forward, Eclipse Threads work in every biome, including all the ones you’ve already visited.

How to Use Eclipse Threads

Using an Eclipse Thread is straightforward. Approach any glowing energy line in the environment and press L1 — the same button you use for dashing. Arjun will zip along the beam at high speed and land at the other end instantly.

There are a couple of things to keep in mind:

• The Eclipse must be active. Eclipse Threads only work when the Eclipse is running in that biome. If the Eclipse has not been triggered on your current run, the threads will not respond. Activate the Eclipse first, then use the threads.
• Threads are two-way. If you approach a thread and nothing happens, you are probably at the wrong end. Every Eclipse Thread can be used from either direction. Walk around and find the other end of the beam — it will trigger from there. This catches a lot of players out the first time.

What Can You Access With Eclipse Threads?

Eclipse Threads open up a lot of content that was locked off during the first half of the game. Here is what becomes reachable:

Ancient Depths Nightmare Strand

The Nightmare Strand in Biome 2 can only be accessed after unlocking Eclipse Threads. In the large central room of Ancient Depths — the same room where you activate the Eclipse Device and explore the two side vaults — there is an Eclipse Thread that leads up to the Nightmare Strand. You cannot reach it any other way.

If you are working toward the Gold Nightmare Strands trophy, this is one of the seven you need to complete. For a full breakdown of what Nightmare Strands are and how they work, check out our guide on Nightmare Strands explained in Saros.

Hidden Rooms and Side Paths in Earlier Biomes

Those faint white lines you saw in Shattered Rise and Shattered Descent? They are all now active. Go back to earlier biomes on a fresh run and look for Eclipse Threads near side rooms and elevated platforms. Many of these lead to containers, Halcyon, and audio logs that were completely out of reach before.

Desecrated Fortress Upper Levels

Inside the Desecrated Fortress itself, Eclipse Threads are not just for exploration — they are required for progression. To reach the boss, Architect, who waits at the top of the highest spire, you need to combine Grapple points and Eclipse Threads to work your way up the structure. The final approach to the boss arena involves a short platforming sequence built entirely around these two traversal tools working together.

Additional Loot and Audio Logs Across All Biomes

Eclipse Threads frequently lead to off-the-beaten-path sections that contain Artefacts and lore items. If you see a glowing line heading somewhere unusual, it is almost always worth following. These side areas exist specifically to reward players who go back and explore once they have the full traversal toolkit.

Eclipse Threads vs Grapple — What’s the Difference?

Both tools help you reach areas that would otherwise be inaccessible, but they work differently:

• Grapple: Launched at purple or blue floating anchor points on demand. You aim and fire. More flexible in combat. Grants invulnerability mid-swing.
• Eclipse Threads: Fixed lines built into the environment. You ride them as-is with no aim required. Cover much longer distances than a single grapple. Only active during Eclipse.

The two tools complement each other well. In the upper levels of Desecrated Fortress, you will use both in the same sequence — grappling between anchor points and then riding threads to cover the bigger gaps between towers.

Tips for Using Eclipse Threads Effectively

• Trigger the Eclipse first. This sounds obvious, but it is easy to rush into a biome and forget. Threads will not react until the Eclipse is active. Make activating the Eclipse Device a priority every run.
• Look for faint lines near dead ends. If you see a gap with no obvious crossing and no grapple point, scan for a thin glowing line. The visual is subtle — it blends into the environment more than grapple points do.
• Try both ends. If a thread is not responding, walk to the other side of the room and look for where the beam originates. The prompt only appears when you are at a working end.
• Revisit old biomes. Shattered Rise and Ancient Depths both have Thread-locked areas. Once you have the ability, go back and clear what you missed. You will find Halcyon and collectibles that improve your overall progression.
• Use them to access Nightmare Strands. The Ancient Depths Nightmare Strand specifically requires Eclipse Threads. If you are working toward the Gold trophy, make a point of doing this one once the ability is unlocked.

Eclipse Threads and the Nightmare Strands Trophy

Completing all seven Nightmare Strands earns the Gold “Nightmare Strands” trophy. Two of the seven — the one in Shattered Rise and the one in Ancient Depths — have extra access requirements. The Ancient Depths one needs Eclipse Threads. The Shattered Rise one needs the Grapple.

Both are available on every run once the prerequisites are met, so there is no rush. But if you want to knock them out efficiently, head back to Ancient Depths with the Eclipse active as soon as you unlock Eclipse Threads in Desecrated Fortress.

For the full trophy list and how to work toward Platinum, see our complete Saros Trophy Guide.

Other Permanent Abilities in Saros

Eclipse Threads is one of several permanent traversal and combat abilities you unlock through story progression. Here’s where each one sits in the game’s progression:

• Jump Network — Unlocked after defeating Prophet in Biome 1. Enables fast travel between discovered points.
• Grapple — Unlocked at the start of Shattered Descent (Biome 3) via a Soltari terminal.
• Overdrive — Unlocked mid-way through Shattered Descent after speaking to Eli. A powerful charged attack triggered with L3 + R3.
• Parry — Unlocked in Blighted Marsh (Biome 4) after completing a task for a character named Alab. Lets you deflect red projectiles back at enemies.
• Eclipse Threads — Unlocked in Desecrated Fortress (Biome 5) via the Eclipse Device and golden item pickup.
• Blazing Strike — Unlocked automatically upon entering Yellow Shore. Enhances your melee attack and lets you break yellow barriers and containers without a key.

None of these are missable. All are locked to story progression milestones and unlock automatically as you play.

Final Thoughts

Eclipse Threads are one of the more satisfying unlocks in Saros because they retroactively open up content you have already walked past. All those gaps and unreachable platforms in the early biomes suddenly become worth exploring. Combined with the Grapple, they give Arjun a full traversal toolkit that makes movement through Carcosa feel fast and fluid.

The unlock itself is simple — reach Desecrated Fortress, activate the Eclipse Device, and pick up the golden item. Everything else follows naturally. Once you have the ability, go back to Ancient Depths first to grab that Nightmare Strand, then work through the rest of the biomes with fresh eyes.

Want to know how long the full journey takes? Our guide on how long Saros takes to beat breaks it all down. And if you have not yet picked up the game, you can find Saros on PS5 via the PlayStation Store.