Dungeon · Levels 8–12
Karkûl-Vesh
The World-Sunk City — a colossal sinkhole where two green dragons hold court over a goblin tribe, and a captured bard plays for his life.
Type
Vertical Dungeon / Sinkhole
Levels
8–12
Depth
400–700 feet
Rulers
Vyrmoss & Kharzûl (Green Dragons)
Inhabitants
Skullcap Goblin Clan
Objective
Rescue Zibbo Croakchord
Adventure Overview
Zibbo Croakchord is missing. The goblin bard — irrepressible, foul-mouthed, surprisingly talented, and catastrophically unlucky — vanished weeks ago in the volcanic jungles of Ravencrest Isle's interior. He is a crew member of the Maiden's Kiss, and the party needs him back. What they'll find is worse than anyone suspects.
Zibbo's trail leads past highland farms and smoking volcanic slopes into jungle so thick it swallows sound. At the jungle's heart lies Karkûl-Vesh — once a thriving goblin trade city built along a river gorge. Three centuries ago, the earth opened and swallowed it whole. The ruins now form a vertical dungeon: the Rim at the top, the Hanging City in the upper ring, and the Drowned Cathedral at the bottom where the waterfall's final plunge feeds a black pool.
A mated pair of adult green dragons — Vyrmoss the Whispering Rot and Kharzûl the Thornclad — hold court over the Skullcap Clan. The dragons keep Zibbo alive for entertainment. The goblins keep him fed because they like his songs. Neither arrangement will last.
Who Is Zibbo Croakchord?
A goblin bard of the College of Lore — fifth level, criminal background, chaotic neutral, possessed of a Charisma score that has no business living in that body. Born in Scuttler's Cove, cousin to Grib Sharptooth the Pirate King. He signed on with the Maiden's Kiss and found something like a home — until his luck ran out. Captured during a shore raid, sold to slavers, purchased by a Fort Valiance expedition as a "jungle guide." He'd never seen a jungle. Now the Skullcap goblins have begun weaving him into their mythology as the Song-Bringer.
The Road Inland
The Whispering Jungle is not a normal forest — it is a green dragon's lair. The entire jungle, corrupted and controlled. Trails shift, landmarks drift, streams change course. Every path eventually comes out at the sinkhole. The dragons designed it that way. Each day: DC 15 Wisdom (Survival). Three consecutive failures mean the party arrives exhausted with an ambush waiting.
1.
Wyvern Patrol — 2 Goblin Wyvern Riders circle the canopy. DC 14 group Stealth to avoid detection.
2.
Toxic Bloom — Dragon-corrupted flowers exhaling green vapor. DC 14 Constitution save or poisoned 1 hour.
3.
The Doomed Camp — Fort Valiance's final camp. Thorne's journal: 'The pit is real. Gods help us, so are the dragons.'
4.
Goblin River Traders — Skullcap goblins on a crude raft. They know Zibbo as 'the Noisy One.'
5.
Swamp Crossing — Goblin Trapsetter ambush in waist-deep muck. 4 Trapsetters with advantage on first attacks.
6.
Dying Soldiers — 1d3 poisoned Fort Valiance soldiers, delirious, babbling about 'two dragons that argue like a married couple.'
Dungeon Levels
The Rim
Entrance
A ring of broken masonry, toppled mask-statues with gouged-out eyes, and shattered causeways. The canopy seals the rim like a lid on a pot. Visibility is limited to gaps where sunlight stabs through in theatrical shafts. Drake-servitors and dinosaurs patrol the upper stair like cattle dogs — pushing intruders deeper, not fighting to kill.
The Grand Stair
Descent — 250 feet
Switchback treads, cracked but stable. The real danger isn't the climb — it's what's herding you down it. Guard Drakes and an Allosaurus drive intruders toward the Hanging City. Alternative descents: the Waterfall Face (DC 16 Athletics, unguarded but treacherous) or the Root Weave (DC 13 Athletics, advantage on Stealth).
The Hanging City
Balconies of Masks
Terraces cling to the chasm wall like ribs, collapsed bridges dangle like snapped vertebrae, vine curtains sway in slow arcs that break sightlines and create rooms that weren't there a moment ago. Goblin fortifications, the Waterfall Basilica, and the Sunken Market. The goblins are conflicted — they fear the dragons but have grown protective of Zibbo.
The Drowned Cathedral
The Throat Below
The waterfall's final plunge feeds a broad black pool that narrows into a stone river-throat. The air is always wet, green, and faintly sweet — the jungle learned to perfume poison. Here the dragons keep their hoard: immovable art, mask-idols displayed like trophies, with gems scattered in cracks like crumbs. And on a dry island of treasure between two dragons, Zibbo plays his lute.
Key Areas
The Watchtowers
4 Goblin Mask-Sentinels, 2 Trapsetters. Alarm horns in both towers — if sounded, the entire Hanging City goes on alert.
The Skullcap Warren
Clan living quarters. 30+ non-combatants among dragon-bone decorations and crude paintings depicting Zibbo as the Song-Bringer.
The Poison Garden
Venommother Skatha negotiates first, fights second. She's grown fond of Zibbo's music and will trade intelligence for a promise to take him safely away.
The Waterfall Basilica
A Driftglobe and Potion of Water Breathing. Faded frescoes depict Sethys, a forgotten river god the goblins carved into everything before the dragons came.
The Sunken Market
2–4 feet of water (difficult terrain). Reflection Traps create false images. Deep Pockets of 10-foot-deep toxic water. Remains of the Fort Valiance expedition.
The Serpent Gate
Pressure-triggered Poison Spray vents (6d6 poison, DC 15 Con half). Venommother Skatha warns the party about this if they negotiated with her.
The Art-Hoard Galleries
2,400 gp in art objects, a Cloak of Elvenkind, and the Mask of the Serpent Oracle (Suggestion 1/day, advantage on Insight, speak Draconic).
The Drowning Throne
The dragon lair. Zibbo performs on a pile of gold between two dragons who can't agree on what he should play next.
The Dragons
Vyrmoss the Whispering Rot
Adult Green Dragon
The cunning one. Uses Poison Breath from concealment, casts Greater Invisibility, and Dominate Person on the healer. Finds Zibbo's terrified performances 'delightful.' Respects draconic traditions like the Performance Duel.
Kharzûl the Thornclad
Adult Green Dragon
The violent one. Does terrifying flybys with Frightful Charge, targets the heaviest armor, and uses Frightful Presence to scatter parties. Vain and aggressive — doesn't care about traditions and may attack anyway.
The Two-Strike Plan
Strike 1 — "Taste the Intruders"
Upper/Mid levels. Breath through fog, a glimpse of scales in a sunbeam, then gone behind vine curtains. Testing who panics, who clusters, who chases.
Strike 2 — "Now You Don't Leave"
Lower city. Water and vines trap. Routes seal. Vyrmoss casts Greater Invisibility and Dominate Person on the healer. Kharzûl charges the heaviest armor.
Hanging Vines
Vine curtains whip out like green tongues. Each creature within 10 feet of a wall: DC 15 Strength save or restrained until next round.
Drowned Dead Rise
1d4 zombies jerk upright from waterlogged corpses in vine tangles. They last one round, then collapse.
Mistblind
Sudden burst of waterfall spray. 20-foot sphere, heavily obscured until next round.
Rescuing Zibbo
Direct Combat
Fight both dragons simultaneously. Extremely dangerous. Zibbo contributes Vicious Mockery when he remembers he knows it.
Stealth Extraction
Vyrmoss naps after meals. DC 16 group Stealth. Zibbo cooperates enthusiastically but is terrible at being quiet (disadvantage on his own Stealth).
The Performance Duel
Invoke serpent courtesy — a draconic tradition Vyrmoss respects. DC 17 Performance to negotiate Zibbo's release. Kharzûl may attack anyway.
Divide & Conquer
Lure Kharzûl through the collapsed dome with a distraction (he's vain and aggressive), then fight Vyrmoss alone. Kharzûl returns in 2d4 rounds.
The River Escape
Grab Zibbo and jump into the River Mouth. Desperate, dangerous (6d6 bludgeoning, 3 miles downstream), but the dragons can't follow through the narrow basalt channel.
Magic Items
Wyvernfang Glaive
Rare
+1 glaive. On hit: +1d6 poison. Once per day (bonus action): next hit forces DC 14 Con save or poisoned 1 minute.
Mask of the Serpent Oracle
Rare
Jade serpent mask. Cast Suggestion (DC 14) 1/day, no components. Advantage on Insight. Speak and understand Draconic.
Zibbo's Lucky Lute
Uncommon
Battered lute that survived pirates, slavery, and dragon breath. Charm Person (DC 13) 1/day while playing. Once per long rest, reroll a failed Performance check.
Treasure Hoard
The dragons' combined hoard: 8,000 gp, 1,200 pp, gems worth 3,500 gp, the Wyvernfang Glaive, a Potion of Vitality, a Scroll of Wall of Thorns, a +1 Shield, and Commander Thorne's +1 Longsword (in Grizzik's possession in the Hanging City above).
Conclusion
If rescued, Zibbo is overwhelmingly, annoyingly, desperately grateful. He launches into a rambling account of his captivity that includes detailed critiques of each dragon's musical taste. He smells terrible. He's missing a tooth. His lute has a crack in it. He's never been happier to see anyone in his life.
Returning Zibbo to the Maiden's Kiss restores a crew member, a friend, and — if he can be convinced to share it — the map of the Central Islands that's been locked in his head since Scuttler's Cove. That map might be worth more than everything in the dragon's hoard.