The Fourth-Floor Swamps are defined less by a single landmark than by the hostile conditions that make them valuable and nearly unapproachable. Their murky water conceals swarms of Relic Worms, transforming a hunting expedition into a contest against an environment that can erase a Climber’s equipment, power, and life without warning. The swamps therefore function as both a physical region and a test of whether exceptional strength can replace technological protection.

Environment and Threat

The swamps conceal Relic Worms in water so opaque that Climbers wade into danger before they can properly see it. The worms attack the legs in swarms of tens of thousands, making movement itself the trigger for an assault. Their numbers turn the wetland into a distributed hazard rather than a battlefield with one identifiable enemy: a Climber is surrounded, exposed, and vulnerable across every step.

The creatures are individually small, palm-length and thin as a few hairs, but their bodies burrow through flesh and Relics with equal voracity. That parallel is crucial to the swamps’ menace. Armor and weapons do not create a secure boundary between person and environment; the worms can invade the body or the equipment meant to protect it. The swamp’s concealment and the worms’ minute size delay recognition until the danger has already become intimate.

Relic Worms and Climber Economics

Relic Worms are technically Floor-Four monsters, but local infamy makes them unusually difficult to hunt. Their defining danger is that they infest a Climber’s Relics, disabling them and abruptly converting what seemed like a normal hunt into a fight for survival. A worm swarm can eat through boots or a weapon, causing a loss of power at precisely the moment the Climber needs it most.

This danger creates an inverted value proposition. Low-level Climbers die in the swamps, while high-level Climbers generally refuse to risk extremely valuable Relics for creatures of comparatively modest worth. The loss is not merely financial: the sudden failure of a weapon or defensive item can expose even a powerful Climber to lethal danger. The wetland thus punishes dependence on equipment while making equipment the most obvious reason to avoid entering it.

Only Climbers powerful enough to subdue Relic Worms without using Relics might hunt them safely. Yet those Climbers would ordinarily have a Demesne in the upper Floors, where more profitable opportunities await. The swamps remain dangerous not because their prey is priceless, but because its value is insufficient to justify the risk for everyone capable of managing it.

William Oh’s Intended Expedition

The Relic Worms nevertheless offer William Oh a reward of exceptional importance: an upgrade to his Phantom Hand promising obscene power. That prospect changes the calculation. Where other Climbers see a poor return and an unacceptable chance of losing valuable equipment, William sees a specific improvement to an ability central to his own fighting method.

The decision also establishes the Fourth-Floor Swamps as a destination William must reach through personal capability rather than ordinary commercial logic. He cannot simply outsource the hunt to stronger Climbers, because the people best equipped to survive it have little reason to accept the job. The swamp therefore becomes a proving ground for a Climber willing to pursue a modestly valued monster because its particular reward fits his Build.

Wider Pattern of the Fourth Floor

The Fourth-Floor Swamps belong to a broader Floor in which danger repeatedly appears as a problem of hidden systems and unstable scale. Elsewhere, workers can seem to materialize in numbers and be driven through lines of fire, while other threats take the form of tiny motes that burn through armor or organisms that multiply from their own writhing bodies. Against that backdrop, the Relic Worms are especially disturbing because their swarm is both ecological and technological: tens of thousands move through the water, then cross the boundary into a Climber’s body or Relics.

The swamps consequently make the Tower’s progression system feel less like a simple ladder of stronger opponents than a sequence of environments that expose different kinds of weakness. Level and equipment are not absolute protections. In the wetland, the strongest visible advantage may become the point of failure, and survival depends on possessing enough power to fight without relying on the Relics that normally define a Climber’s strength.