Tunnel Rat Extermination

Location: Sub-Terran Accord – Mining Sector 4 (The Deep-Strands) Level Range: 1-2

Background & Objective

Giant rats have nested in a critical delivery chute within the Sub-Terran Accord’s mining sector. While a "simple" extermination job on the surface, this chute is a primary artery for transporting raw ore and Aether-glass components. The chute is a mere 3 feet wide, making movement and combat awkward for larger folk.

The infestation is not merely a nuisance; localized Aether crystal seepage from a nearby tectonic shift has caused the vermin to grow aggressive and erratic. These mutated pests are hoarding glowing, volatile shards within the cramped confines of the chute. Clearing the infestation is essential to restoring the flow of ore and investigating the source of the crystal contamination before the volatile Blue Bile secretions cause a structural collapse.

Key NPC: Overseer Snag-Tooth

A high-strung kobold engineer with a brass-plated tail and a monocle made of polished Aether-glass. He is responsible for the maintenance of the delivery chutes.

"The chute is the vein, the ore is the blood. These rats? They're a clot we need lanced, and fast! Watch your head—and your shins."

Ideals & Flaws

• Ideal (Efficiency): "Every second the chute is clogged is a second the Great Mycelium goes hungry for data."
• Flaw (Arrogance): Snag-Tooth has a deep-seated bias against "Tall-Folk" and constantly mocks their lack of spatial awareness in tight corridors.

Rumors & Whispers

• True: The rats aren't just nesting; they are being driven into a frenzy by a leak of Blue Bile, the caustic, magically volatile coolant produced by the Omnisporangium.
• False: The rats are actually polymorphed spies sent by the Steam Wrights Consortium to sabotage the Sub-Terran Accord’s production.

The Gimmick: Cramped Spaces

The delivery chute is a Medium creature's nightmare. Throughout the encounter, the following rules apply:

• Squeezing Rules: Large and Medium creatures must "Squeeze" to move through the 3-foot wide chute. This results in disadvantage on attack rolls and Dexterity saving throws. Movement costs double.
• Verticality: Rats have a climbing speed and can move across the ceiling and walls, allowing them to bypass the "front line" and attack casters in the back.
• Narrow Line-of-Sight: The slight curves in the chute and the clutter of hoarded ore make ranged combat difficult; any target more than 15 feet away has half-cover.

Sensory Details: The Deep-Strands

Sight, Sound, and Smell

• Sight: Flickering, rhythmic pulses of bioluminescent blue light emanate from the rats' eyes. The walls of the chute are etched with brass Reinforcement rings and stained with a glowing, viscous cerulean slime.
• Sound: The metallic hissing of steam pipes overhead, the frantic scratching of claws against copper plating, and the occasional high-pitched, harmonic "chirp" of raw Aether shards.
• Smell: An acrid mixture of ozone, wet rodent fur, and the sharp, chemical tang of Blue Bile.

Markings

Scratched near the entrance of the chute is a series of three jagged horizontal lines intersected by a vertical claw mark.

• Translation: "Small-path only; lungs-burn ahead." (A Sub-Terran warning about cramped spaces and gas/Blue Bile fumes).

The Monsters: Bile-Touched Giant Rats

These rats have been altered by the Aether seepage. They are larger than average, with patches of translucent skin revealing glowing blue veins.

Tactics

The rats utilize their environment perfectly. They prefer to drop from the ceiling onto the heads of "Squeezing" adventurers. If a rat is reduced to half its hit points, it may attempt to "shatter" a hoarded Aether shard, creating a 5-foot burst of Wild Magic or Blue Bile spray to cover its retreat.

Ecology

Normally, these rats are simple scavengers. However, the Omnisporangium’s recent "immune response" has pushed Aether and Blue Bile into the upper crust. The rats have become accidental "Blue-Bile Mutants," acting as a localized infection within the Sub-Terran Accord’s mechanical systems. They are drawn to the magic of the Aether shards like moths to a flame, though the energy slowly destroys their nervous systems.

Narrative Outcomes & Loot

The success of this mission ensures the safety of the Sub-Terran Accord’s infrastructure. Overseer Snag-Tooth will grant the party a Letter of Introduction to Grand Warren-Master Zik-Zik, providing significant political favor within the region.

Featured Item: The Accord Chisel

• Lore & Origin: This tool was forged by the Aether-Weaver Goblins in the Crystal Forge. It was originally designed to harvest pure Aether crystals without triggering a resonance explosion. Its handle is wrapped in Mycelial-thread, which hums when near high concentrations of magic.
• Mechanic: A magical tool that grants advantage on checks made to disable mechanical traps or harvest magical crystals. Once per day, it can be used to "vent" a magical source, granting the user resistance to force damage for 1 minute.

Connection to the Omnisporangium Cycle

While this appears to be a mundane pest problem, the Aether seepage in the chutes is a direct result of the First Brood's awakening elsewhere. The pressure in the subterranean leylines is rising, forcing the Omnisporangium to flush "Blue Bile" through these secondary delivery routes. Clearing the rats is the first step in realizing that the very plumbing of the world is beginning to burst.