Bungie has shared a detailed look at Expedition, the new permanent PvE mode coming to Marathon with the Symbiosis update on December 8, 2026. Unlike the game’s traditional extraction experience, Expedition removes the threat of enemy players and introduces a cooperative roguelite system where Runners can focus on fighting AI enemies, completing objectives, and building powerful loadouts.
In its latest developer deep dive, Bungie revealed how Expedition’s three-run structure works, alongside new Flash Boost upgrades, challenging encounters, and rewards that carry over into the main Extraction mode.
In Brief:
- Marathon’s Expedition is a permanent cooperative PvE roguelite mode launching December 8, 2026, with the Symbiosis update.
- Players can enter solo, as a duo, or in a trio and work alongside other Runner crews without PvP encounters.
- Each Expedition features three increasingly difficult runs, new Flash Boost upgrades, and a final challenge called the Critical Incident.
- Players can earn credits, XP, materials, Schemas, and other rewards that contribute to progression in Extraction.
Marathon’s New Expedition Mode Offers a PvE-Only Experience
In its latest developer deep dive, Bungie confirmed that Expedition will have its own dedicated matchmaking queue, separate from Marathon’s traditional Extraction mode.
The new mode focuses entirely on cooperative PvE gameplay, letting players explore Tau Ceti IV without worrying about getting ambushed by hostile Runners.
Players can queue alone, with one friend, or as a full three-player crew. Multiple Runner crews will also share the experience, working toward objectives while facing increasingly dangerous AI enemies.
Expedition will support four locations:
- Perimeter
- Night Marsh
- Outpost
- Cryo Archive
Players can choose which location to visit during each run, provided they have unlocked the area through their Runner Level.
Priority Contracts will also be available in Expedition, allowing players to progress through the game’s story and uncover more mysteries without participating in PvP.
How Expedition’s Three-Run Series Works
At the center of Expedition is a new system called Run Series, which consists of three consecutive runs with increasing difficulty.
The goal is to gradually develop a stronger build before tackling the final challenge.
Here’s how the system works:
- Run 1: Explore the map, complete contracts, collect loot, and start building your loadout.
- Run 2: Continue improving your equipment and Flash Boosts while preparing for harder encounters.
- Run 3 (Critical Incident): Face the toughest challenges in the series, with adjustable difficulty and better potential rewards.
The final run, known as the Critical Incident, introduces tougher activities and encounters.
Depending on the chosen location, players can attempt challenges such as:
- Completing the Upper Complex activity in Night Marsh.
- Accessing the Pinwheel in Outpost.
- Fighting the new Tick Queen enemy in Perimeter.
Players can increase the difficulty of these encounters for better rewards.
Interestingly, completing a Run Series doesn’t mean the adventure has to end. Players can cash out their rewards or continue into another series to push their builds even further.
Bungie also confirmed that players can reset their series at any point to collect their current rewards or start fresh.
If someone joins a crew already progressing through a series, they’ll enter at the crew’s highest current run. However, they’ll be limited to faction loadouts rather than a build developed across earlier runs.
Marathon Expedition Introduces New Flash Boost Upgrades
One of Expedition’s biggest additions is a new progression system called Flash Boosts.
These upgrades are designed to make each Run Series feel different by allowing players to experiment with new builds and power combinations.
Flash Boosts can be obtained by:
- Exploring and looting different areas.
- Defeating powerful enemies.
- Completing objectives during a run.
Players can also stack multiple copies of the same Flash Boost to increase its rarity and effectiveness.
This means players can progressively strengthen their builds across a Run Series, potentially creating powerful combinations before reaching the Critical Incident.
Faction Run Kits and Loadouts Explained
Expedition will also introduce a dedicated Run Kit system.
Each faction will offer its own starting loadouts focused on different weapons and playstyles.
Players will begin with a basic faction loadout, which remains locked for the duration of their Run Series.
However, that doesn’t mean players are stuck with their starting equipment.
Weapons and other items can still be found, upgraded, and improved throughout the series.
As players progress, they’ll also unlock faction upgrades that improve their starting loadouts for future Expeditions.
The combination of faction kits, loot, and Flash Boosts should give players plenty of opportunities to experiment with different builds.
What Rewards Can You Keep From Expedition?
Bungie also clarified how loot and progression will carry over from Expedition into Marathon’s main Extraction mode.
Although most equipment collected during a Run Series will be automatically sold when the series ends, several rewards and progression systems will carry over.
According to Bungie, players will be able to keep the following:
- Materials: Successfully extracted materials will go to the Vault and can be used for faction upgrades.
- Run Series rewards: Reward packages will grant additional materials, while higher-tier packages may also contain equipment that can be brought into Extraction.
- Schemas: Schemas unlocked in Expedition will also become available in Extraction.
- Collectibles: Collectibles discovered during Expedition will count toward Codex progression.
- Credits and XP: Earned credits and experience will carry over, helping players purchase equipment and improve their Cradle.
- Cradle upgrades: Eligible gear transferred to the Vault can also be used to upgrade the Cradle.
Flash Boosts and most regular equipment collected during a Run Series won’t transfer directly into the player’s Vault, as they will be sold when the series ends.
However, gear awarded through higher-tier Run Series reward packages can be used in Extraction.
This means players can make meaningful progress through PvE while preparing for more dangerous encounters in the main game.
Perimeter Gets Two New Areas and the Tick Queen
Alongside Expedition, the Symbiosis update will bring a major overhaul to Perimeter.
The map will feature extensive fungal growth, giving the area a completely different appearance while introducing two major locations:
- Reservoir: A new area within the redesigned Perimeter.
- The Burrows: Another major location expanding the map’s explorable spaces.
Players will also encounter the Tick Queen, a new enemy featured as one of Expedition’s Critical Incident challenges.
According to Bungie, the redesigned Perimeter will become the map’s permanent appearance going forward.
Existing contracts will remain playable despite the changes.
When Is Marathon Expedition Coming Out?
Marathon’s Expedition PvE mode will officially launch on December 8, 2026, alongside the Symbiosis update.
Bungie will also host an Open Play Week from December 8 to December 15, allowing players to experience the game and its new content without purchasing it during the promotional period.
The developer plans to share more details about Expedition and Symbiosis in its next Dev Insights presentation on December 1.
Meanwhile, Expedition Phase 2 is expected to receive additional details in March 2027, with Bungie planning to continue developing the mode based on player feedback.
And with its roguelite progression, difficult boss encounters, and rewards that feed into Extraction, there’s plenty of reason for existing players to give the new mode a shot.
