4. **Break.** The release is resolved: everything it sent into the room is cleared, or you complete a seal that closes its source. Killing faster than bodies arrive keeps a lane clear, but it does not stop a source that is still feeding. You can also get out past a bulkhead or outrun the woken area — that saves you, though it resolves nothing. Closing a source stops its incoming flow but leaves creatures already inside active. Once the current space is cleared or safely separated from them, the music and room silhouette release, and the lull belongs to looking, salvaging and deciding where to go.

Crowds come from **source areas**: wards, lift wells, ducts, flooded concourses, sealed volumes — places that physically hold bodies and connect to the route you are on. Bodies always arrive through routes you can see or hear. Crowds do not materialize without a physical approach, and no extra wave arrives because your build was efficient. A warned route can still carry enemies around or behind you.

Each source releases its crowd in **stages**: a finite surge the room announces, from a source you can identify. While a stage is feeding, out-killing it keeps a lane open but does not stop it. It ends when you clear everything it sent, or when you complete a physical seal that closes its access. Walking away ends your part in it, not the stage. A further stage exists only where the room announces and sources one — a machine waking, a new mouth opening. Finite sources are fine; what the design avoids is an encounter that is over after five enemies. Sources feed through apertures — grilles, hatches, ward doors, ducts — that are separate from the passages you walk through, so sealing one never closes a route you need.

**Scale, as a hypothesis.** In a broad ward, dock or gallery a developed crowd might show 80 to 150 bodies at once and pass several hundred through its full crest. A narrow corridor shows fewer at once but a continuous river through doors, lifts and ducts. A small room can host a short teaching moment — one new creature, one new warning — but the way to it still carries the crowd. Where a placed room is too small for the crowd its encounter needs, that is rework to do, not free capacity; [Encounter And Mechanism Placement Inventory](/Hold%20The%20Flood/Encounter%20And%20Mechanism%20Placement%20Inventory) lists those obligations.

Noise and machinery wake the next stage. Loud work, alarms and a Caller that finishes its call can each wake an adjacent source, and its route is always shown before the crowd arrives. Cutting an alarm, stopping a Caller or sealing the answering aperture first prevents that stage; bodies already on their way keep coming.

Letting it happen can be a choice, too. A player with a strong build may want the second surge. Deliberately waking a large machine brings a much larger surge and often reveals new space — [The Game](/Hold%20The%20Flood/The%20Game) shows one.

Clearing the current space, or safely separating it from remaining threats, earns a lull: time to investigate, salvage and choose a route. A source seal can earn its upgrade while creatures already inside remain dangerous; sealing never deletes those creatures. The room shows whether each source is sealed, spent or still able to release another announced stage. You can resolve a stage early, too — clear the first arrivals before the peak, or seal the source before its crowd fully arrives — and that counts at once; there is no need to wait for danger. Or you can simply get out past a bulkhead or outrun the woken area.

Quiet does not last forever. An occupied area next door can still send bodies through a visible route, with sound and door movement to warn you. But a stage you resolved does not come back by itself.