Sump Rat Swarm

Senses: Sees normally in total darkness

Chittering Tide. The swarm can occupy other creatures' spaces and flow through any gap a rat could fit. It takes half damage from single-target attacks and full damage from area effects and flame.

Filth-Borne. A creature that is already wounded when bitten by the swarm makes a Toughness Save DC 11 or contracts sump-rot, taking Disadvantage on Toughness checks and Saves until treated with a Medicae check DC 12.

Gnawing Mass. Melee Attack: +3 to hit, reach 0 ft., one creature in the swarm's space. Hit: 1d6 piercing damage, or 2d6 piercing damage if the target is Prone, Grappled, or Bleeding.

Boil and Scatter. The swarm surges through a 10-foot zone. Each creature in the zone makes a Willpower Save DC 11 or is Pinned by panic until the start of its next turn.

Morale: Instinctive: disperses from flame, bright light, or the loss of half its Vitality, then re-forms two corridors away where the food is.

Tactics: Arrive mid-fight, flow toward the bleeding, and make the floor unreliable. Flame and area weapons clear it fast; the question is what those solutions cost in a promethium-soaked tunnel.

Loot / Evidence / Hooks: Nothing on the rats, but their nest-heaps collect whatever the underhive's dead were carrying — teeth, cogs, and the occasional signet ring.

A Sump Rat Swarm is the underhive's oldest tenant: a chittering carpet of vermin that turns wounds septic and composure optional. It is rarely the mission and often the reason the mission went wrong.

Use this enemy as ambient underhive pressure — a complication during a fight, a hazard in the dark, a tax on the wounded.

Swarm resilience against single-target attacks, weak damage, disease on bites, panic pressure, flees from fire and light.

Chittering Tide. Occupies enemy spaces and flows through any gap; half damage from single-target attacks, full damage from area and flame.

Filth-Borne. Its bites carry sump-rot: wounded creatures bitten make a Toughness Save or take a lingering disease effect.

Gnawing Mass. Engulfing bite attack; deals extra damage to prone, restrained, or already-bleeding targets.

Boil and Scatter. Surges through a zone, forcing Willpower Saves against panic from anyone underfoot.

Morale: Instinctive: disperses from flame, bright light, or heavy losses, then re-forms two corridors away where the food is.

Tactics: Use the swarm to complicate rather than headline: it arrives mid-fight, targets the bleeding, and makes floors unreliable. Flame and area weapons clear it fast — the question is what else those solutions cost in a promethium-soaked tunnel.

Full Stat Block Priority: Low