Story Summary (for GM)
The Black Star Cult is collapsing tunnels leading to gem-rich, high-magic chambers deep beneath the city. In sealed chambers, they use arcane anchors and rituals to summon or breed horrors. Their ultimate goal: fill the deepways with twisted monsters and unleash them under Khur Dural in a coordinated attack.
This mine contains one such corrupted zone, already destabilized and partially sealed. The dwarves believe goblins are to blame. They’re wrong.
Room 1 – The Violet Vein
Read aloud:
The cavern walls shimmer with veins of faintly glowing violet crystal. Pickaxes lie abandoned where they fell. A dull hum rises in the silence, subtle but constant, like pressure behind your eyes.
Key Details:
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Crystals: Mythrilite (volatile, magical crystal that amplifies arcane energy).
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DC 13 Arcana: Crystals are unstable due to nearby leyline disruption.
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DC 14 Investigation: Burned pickaxe haft bearing Black Star glyph (spiral and triangle).
Optional Combat:
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2x Grimlocks (MM p. 175), corrupted. Attack if crystals are touched.
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Visually warped—veins pulsing with black-purple glow.
Room 2 – Collapsed Chamber
Read aloud:
Collapsed stone chokes the tunnel ahead. Scorch marks blacken the walls, and spiderwebs glisten in the corners. The air smells of burnt dust and damp fur. Threads twitch along the ceiling.
Combat Encounter:
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1x Ettercap (MM p. 131) – corrupted, cult markings on carapace.
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2x Giant Wolf Spiders (MM p. 330) – crawl from above, eyes glowing faintly purple.
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Spiders gain advantage on first attack if an ally dies.
Environment/Clues:
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DC 12 Investigation: Rune-etched obsidian spike half-buried in wall, emitting faint whispers.
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DC 14 Arcana: Spike drains natural magic, destabilizes stone.
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DC 13 Survival or Engineering: Collapse wasn’t natural—designed to bury access to a gem-rich branch.
Optional Loot:
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Folded note with diagram of sealed tunnels marked “SEAL, INFECT, BREED”
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Small iron ring with the Black Star symbol
Room 3 – Ritual Site
Read aloud:
Six blackened stones encircle a cracked floor. Ash and melted wax streak the rock. A wide smear of blood leads to the center, where a crude arcane symbol is burned into the stone.
Combat Encounter:
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1x Cult Fanatic (MM p. 345), wears black-thread robes
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2x Shadows (MM p. 269), summoned guardians
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The fanatic chants mid-fight: “The womb opens below. The stone bleeds.”
Clues:
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DC 12 Religion: Symbols are part of Black Star summoning rituals.
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DC 15 Arcana: A dimensional seep—used to weaken boundaries between planes and allow incursion.
Room 4 – The Glowing Pool
Read aloud:
The cavern opens around a wide, shallow pool. The water glows from beneath with a pale blue-green light. Something stirs below the surface, slow and rhythmic, like breathing.
Combat Encounter:
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1x Veilbelly Horror (reskinned Otyugh, MM p. 248)
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Necrotic tentacle attacks
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On death: psychic shriek, DC 13 WIS save or 1 level of exhaustion
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Mechanics:
- Pool is magically volatile. Casting a spell within 10 feet requires a DC 12 CON save or take 1d6 force damage.
Clues & Loot:
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Ritual scroll sealed in glass tube (Magic Circle or Summon Undead)
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Fragment of a dwarven pendant: crest of a missing mine foreman
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Mythrilite shard (arcane focus, +1 to spell attack rolls underground)
Conclusion / Report Back
Deliver the following findings to King Brundrik:
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Cultists are using obsidian arcane anchors to collapse and seal key magical chambers.
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They’re summoning or breeding monsters in these sealed chambers.
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The mine isn’t just being attacked—it’s being turned into a launching point for a full-scale assault from below.
Let me know if you’d like a one-page PDF reference version or maps for each room.