Access the Ancient Sewers branch and its distinct encounters on a one-cell run.
PC / Global, base game and installed DLC routes labeled
WHERE & HOW TO FARM
Where to farm
Prison Depths door leading to Ancient Sewers, with one BSC active.
Ancient Sewers is reached through a BSC-gated door in Prison Depths. The route is available only when one Boss Stem Cell is active for the current run. This is a branch choice, not a permanent door unlock: activate the cell before starting, reach Prison Depths, and check the displayed requirement. The route can expose different enemies and blueprint opportunities.
Set one Boss Stem Cell active before leaving the starting tube.
Take a route from Prisoners’ Quarters that reaches Prison Depths.
Explore the biome and look for the door marked with its BSC requirement.
Check that the door is available for the current run; open it when the sign indicates the required count.
Enter Ancient Sewers and continue through the branch’s encounters.
Collect visible cells and any blueprint drops from enemies you are targeting.
At the next Collector passage, spend cells on the blueprint or unlock you selected.
Farming tips
Read the number printed on the door rather than assuming every BSC gate has the same threshold.
Bring a build and health reserve suited to a more demanding branch.
Repeat, collect and use
Repeatable on runs with one BSC active and the route to Prison Depths available. The door is not accessible on a run below its requirement.
Common mistakes
Reaching Prison Depths with zero active BSC; activate the cell at the start of the run.
Looking for Ancient Sewers on a route that bypasses Prison Depths; choose the branch deliberately.
Expecting the route to guarantee a specific blueprint; enemy drops depend on the blueprint still being uncollected.
When to stop or switch
Stop in Ancient Sewers once you have collected the route rewards relevant to your run, then continue to the next biome and spend cells at the Collector.
