This is the most direct “dungeon crawl” style entrance. It’s brutish, dangerous, and unpleasant. The challenge here is endurance and overcoming environmental dangers.
The Plunge & The Mire:
- Description: “The gaping hole in the Terminus platform reveals a rusted iron ladder descending into darkness… The ladder ends in a wide sewer conduit, its floor covered in a thick layer of viscous, grey sludge that bubbles slowly…”
- The Hazard: The grey sludge is Difficult Terrain. We can also add that the chemical stench is nauseating. Each character must succeed on an initial DC 10 Constitution saving throw upon entering or have disadvantage on Wisdom (Perception) checks that rely on smell for the duration they are in the sewers.
Obstacle 1: The Veins of Vitriol
- Description: “Ahead, the main conduit is crisscrossed with faster-moving streams of a pale, ochre-coloured slime that bubble and hiss where they touch rusted metal. As you watch, a rat scurries out of a pipe, touches one of the ochre streams, and instantly dissolves into a puff of acrid smoke.”
- The Puzzle: They must cross a 40-foot section dominated by these hazardous veins.
- Solutions & Skill Checks:
- Acrobatics/Athletics: A character can try to leap between the few stable-looking patches of grey sludge with a DC 14 Dexterity (Acrobatics) check. A nearby character can use the Help action by pointing out a path, or a character can try to throw a rope to assist, requiring a DC 13 Strength (Athletics) check to secure it.
- Investigation/Arcana: A DC 14 Intelligence (Arcana) check reveals the slime is highly reactive to kinetic force and intense magic. A success tells them that loud noises or splashy spells are a very bad idea.
- Creative Solutions: Spells like Levitate, Misty Step, or using tools to create a makeshift bridge are ideal here.
- Failure: Failing the check means slipping into an ochre vein, requiring a DC 13 Dexterity saving throw to pull back instantly. On a failure, they take 2d6 acid damage; on a success, they take half.
Obstacle 2: The Gas-Filled Chamber
- Description: “The path forward dips into a lower cistern chamber where a heavy, green-tinged gas has pooled, obscuring the floor. The chemical smell here is overpowering.”
- The Puzzle: The gas is toxic. They must find a way across the 30-foot chamber without succumbing.
- Solutions & Skill Checks:
- Hold Breath: The simplest solution, but if they have to make any strenuous checks (like Athletics) while holding their breath, they must succeed on a DC 10 Constitution check or lose their breath.
- Perception/Investigation: A DC 15 Wisdom (Perception) check might spot a series of maintenance pipes running along the ceiling they could try to cross, hand-over-hand (DC 13 Athletics).
- Creative Solutions: Gust of Wind or similar spells could temporarily clear a path. Throwing a torch in would likely cause a harmless (or perhaps minorly damaging) “whoosh” as the flammable gas burns off briefly.
The Climax: The Jammed Junction Gate
- Description: “You finally reach a massive central sewer nexus. The way forward is blocked by a colossal, rusted iron gate, jammed half-open. A torrent of foul, pressurized water sprays violently through the gap, making passage impossible. A large control wheel on the gate is rusted solid.”
- The Puzzle: They need to stop the torrent of water to get through the gate.
- Solutions & Skill Checks:
- Investigation: A DC 14 Intelligence (Investigation) check of the area reveals a secondary, smaller maintenance tunnel nearby, from which the sound of a working mechanism can be faintly heard. This tunnel leads to a pressure-release valve room.
- The Valve Room: Inside, a large lever is rusted in place. It will require a significant effort to move. This can be a group Strength (Athletics) check (combined DC of 30) where multiple characters can contribute their results, or perhaps it requires using Tinker’s Tools to loosen the mechanism first.
- Creative Solutions: A spell like Grease could lower the DC. Someone might use a crowbar with Athletics.
The Reward:
Once they release the pressure valve, the torrent slows to a manageable trickle, allowing them to slip through the jammed gate. Just beyond the gate is the door to the maintenance office, where they find the map of Layer 2. They have successfully bypassed the main dangers of this route through cleverness and teamwork, but have likely expended time and some resources (HP from failed saves, spell slots for utility).