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Caves of Corrosion

Running the Adventure

  • This adventure is intended for a party of 4-6, 7th level players. You may need to adjust some HP values based on party size.
  • Anything in "Itallics" is meant to be read to the players by the DM.
  • Read through the "DM notes" prior to beginning to get some background information
  • This is intended to act as a guide, to give a basis to a DM for running the adventure. Some blanks will need to be filled in on the fly.
  • Depending on the party composition, you might want to add 2-3 Tithonoloth enemies to the final encounter.
  • Alternatively, you could not allow for a short rest by either having a Tithonoloth interrupt the rest or by indicating the party hears chittering around them that seems to be moving closer
  • Resources such as character creation info, stat blocks, maps and player handouts can be found at the bottom of the article.
Loot Studios Bundles - I have not uploaded photos of the physical battlemaps yet because I have not got around to setting it up for myself. As well, I have not printed all the scatter terrain from Tenebris yet.
  • Tenebris Infested - The enemies and much of the terrain you will want to use will come from this bundle.
  • Goblin Mines - Use the walls from Goblin Mines to make up the battlemap perimeters for tabeltop use.

LEVEL 1: ADMINISTRATION LEVEL

  A-1) Entrance Tunnel: The entrance to Biggarswith Hollow stands half-sunken in a hillside of jagged rock, its weather-worn timbers stained a sickly green. The faint tang of metal hangs heavy in the air, and a metallic, acrid bite stings your nostrils with every breath. Rusted mining carts lie overturned like forgotten toys, their wheels coated in a thin, iridescent film. A low groaning creak echoes from deep within the mine, as if the earth itself were shifting beneath the weight of something unseen. Faintly, you hear the distant drip of water — steady, deliberate, and far too loud for mere condensation.   A-2) Foremans Office: This cramped office is in disarray, with a split desk spilling papers soaked in greenish fluid. A torn mining map hangs on the wall, its features unreadable and claw-like gouges scar the doorframe leading out.
  • Feature: A scrawled entry in a ledger mentions "strange tremors, worse than before" just before the entries stop abruptly.
  A-3) Mess Hall: Broken tables and chairs lie in splintered heaps amid shattered mugs and bowls. A wall tapestry hangs in tatters, half-melted by acid, while faint blood trails lead toward the opposite doorway.   A-4) Storage Room: Shattered crates and collapsed shelves spill corroded tools and ruined supplies across the floor. Green-black sludge seeps through cracks in the stone, and a metal-bound strongbox, tarnished green, is half-fused to the wall.
  • Strongbox Loot: The strongbox is covered in corrosive acid. A player which attempts to unlock it takes 1d6 acid damage. DC 15 Thieves' Tools contains 25 gold pieces, 4 gemstones (worth 50g each), and 2 potions of healing.
A-5) Medical Bay: Rust-covered cots line the walls, their linens dissolved into brittle tatters. Glass vials on a broken shelf are coated in a thin, greenish crust, and the faint coppery scent of old blood hangs in the air.
  • Note: The medical bay is not well stocked or complete. Mostly designed for isolation of sick miners, bandaging cuts and slinging broken limbs.
A-6) Barracks: Rows of simple bunks line the walls, most reduced to warped frames and shredded bedding. Several dead bodies lie scattered across the room, their faces twisted in pain, with burns and holes in their flesh. The stench of copper and rot hangs heavy in the air.
  • Feature: A player with a passive perception of 14 or greater will notice a faint movement from one of the bodies — a subtle twitch of a hand or a weak groan. If the players approach, they will see that this dwarf is still alive, though barely. Otherwise a player who succeeds on a DC 14 Perception/Investigation check will notice the same thing.
  • The players may make a DC 13 Medicine check to recognize that Thorin is severely injured, suffering from acid burns on his face, particularly around his eyes. They also realize that while his wounds are not immediately fatal, he will die without assistance. Stabilizing him requires magical healing or a successful Medicine check (DC 15) using a healer’s kit or improvised materials.
Thorin Silverhammer: Thorin is a middle-aged dwarf with a stocky frame and a once-proud beard now singed and patchy from the acid. His eyes are crusted over with corroded flesh, and his face is marred with scar tissue from burns. His leather mining attire is tattered and corroded in places, especially around his shoulders and arms.
  • Personality: Thorin is hardy and stubborn but also deeply shaken by the events. His voice trembles as he speaks, not out of fear but from the sheer pain of his injuries. He’s slow to trust the party initially, but if the players show kindness or patience, he will open up.
  • Motivation: Thorin wants to know if the other miners are alive. He is desperate to hear good news but will react with sorrow if the party tells him otherwise. His ultimate goal is survival — he just wants to get out alive.
Information
  • Thorin does not recall many specific details of the incident, only that he heard an ear piercing screech followed by a loud crash. As he turned to look in the direction of the noise, he felt a searing pain in his face and the world went black as he fell unconcious.
  • The foreman of the mine had been growing concerned about something, though he did not know what. He ventured into the mines on his own the day before the attack.
  • Later that day, these large, chittering bug-like creatures began coming from some lower parts of the mine. They collapsed several side tunnels on the minin level to cut off their movements and blocked off the tunnel leading below the mining level.
  • It wasnt his call, but the foreman was in the lower levels when they collapsed the tunnels.
A-7) Supply Lift: Description: A winch-operated platform elevator descends to the next level. The wood is scorched in places, and the chains are tarnished with a greenish patina.
  • Feature: The crank on the winch is damaged and will need to be replaced before the lift can be operated. Players may salvage the wreckage to repair the winch with a successful DC 13 Investigation check.
  • Failing to to salvage an appropriate crank will require the players to climb down the supply lift. They may make a DC 14 Athletics check to climb down the cable, on a fail the player falls 30ft and takes 3d6 bludgenoning damage.
  • The crank at the bottom is still intact and can be cranked to activate the mineshaft.

Mining Level

  M-1) Supply Station: Broken crates and rusted tools lie scattered across the floor, and the faint smell of rot mingles with the sharp tang of acid. A warped shelf tilts dangerously, its contents spilled onto the ground below.
  • Loot: 2 intact Pitons and 50ft of usable rope - DC 14 Investigation reveals a hidden compartment beneath a barrel which contains 1x potion of acid resistance and 1x potion of fire resistance as well as 1x scroll of Tidal Wave
M-2) Formans Office: A small chamber with a scorched desk sits at its center, its surface warped and covered in scattered notes. Broken shelves line the walls, their contents spilled and rotting on the floor.
  • Feature: If the players search the desk they will find the foremans notes scattered about. Give them the handouts from the "Scattered Notes" section.
M-3) Collapsed Corridor: As you step into the corridor, the sound of chittering echoes from multiple sources. Ahead, a 30-foot-wide gap spans the tunnel where the floor has collapsed. On the far side, a steep, rubble-covered slope offers a possible way out. Below, in the darkness, chitinous creatures skitter across the debris, their mandibles clicking in an eerie rhythm. The only intact path across is a rusted mining rail, stretching precariously over the gap, creaking under its own weight. In order for the players to get through this corridor, they must either climb 30ft down to the collapsed portion below and fight their way across, or attempt to cross the mining rails which spand the distance of the corridor.   Enemies: (Loot Studios)
  • 3x - Tithonoloth Tunneller Drone
  • 2x - Tithonoloth Soldier Drone
Enemies: (Non Loot Studios)
  • 3x - Ankheg
  • 1x - Umber Hulk
The bugs below will seem oblivious to the party, but if a player touches the ground in the pit below, they will immediately attack.   Skill Challenge
  • DC 15 Athletics or Acrobatics check to attempt to cross the rails. Failing a check will result in the player falling 30ft to the pit below and taking 2d6 bludgeoning damage.
  • Roughly halfway across, the rail will give way slightly. The player nearest to the center must succeed on a DC 14 Athletics saving throw, or fall 30ft to the pit below and take 2d6 bludgeoning damage.
  • If any player falls into the pit below, the creatures will attack.
  M-4) Storge Chamber: Moldy sacks and toppled barrels fill this cramped room, with a thick, sour smell clinging to the air. The walls are streaked with greenish-black stains that trail down from the ceiling.   M-5) Miners Workshop: Heavy workbenches line the room, stained with dark marks and etched with deep gouges. The air reeks of metal and vinegar, and broken hammers and chisels lie scattered across the stone floor.
  • Loot: an intricate looking beard bead that has a strange mental weight to it(see Bead of Enduring) can be found beside an Artisans Kit.
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Trap! - While moving through the corridor between M-5 and M-6
  • As the players walk through the narrow corridor, when one of the players reaches the Y junction of the mine cart track, green acid erupts from the ground. Any creature within 20ft must make a DC 15 dexterity saving throw, taking 3d6 acid damage of a fail or half as much on a success.
  • DC 13 investigation - Preliminary checks will determin that a tunnel created by one of the bug creatures had a pool of acid inside that was then covered by the nearby tunnel collopse. The players movement disturbed the earth surrounding it which caused the pressure from the gasses to erupt outward.
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M-6) Miner's Bunkroom: Ragged bedrolls and dented footlockers are scattered across the floor. The air smells of damp cloth and acid, and faint scratches mark the floor near the back wall. Hidden Loot: DC 13 Investigation - A pair of silver rings in a hidden compartment beneath the lid of one foot locker.
  • One mundaine worth 25gp
  • One Ring of Spell Storing - 1x Cure Wounds, 1x Bless, 1x Guiding Bolt
M-7) MINERS' MESS HALL: Splintered wooden tables and broken chairs are strewn across the room. A large iron pot, now a melted, twisted heap, sits in the center of a stone firepit.   Note: If the players did not fight the enemies in the corridore, they will encounter them in here. If you have lots of time, you could include them here anyway.  
  • Loot: A healing salve (acts as a Potion of Healing) can be found in a storage cupboard (Investigation DC 13).
M-8) Collapsed Chamber: The ground here is broken and uneven, the jagged edges of stone supports circling a wide, dark pit that drops into a vast chamber below, sporadically illuminated with a faint, green glow. A soft bubbling sound echoes from within, and the sharp, stinging acrid smell grows stronger.   Players will need to descend the 60ft drop in order to get to the next level. They can do this by:
  • Utilizing any physical or magical resources at their disposal.
  • A player with darkvision would be able to faintly make out a large pool of water, directly below the opening.
The pool of water below the opening is partially acidic, as a corrosive reaction spreads through it, slowly converting the water into a bubbling, toxic sludge.
  • A creature who enters the pool will recieve 1d6 acid damage upon entering it, as well as for every 10ft they swim in it.
Final Chamber: The cavern expands before you, a vast chamber of jagged rock formations jutting from the uneven ground. Small acidic streams carve winding paths between them, their faint hiss echoing in the air. Scattered throughout the space, pools of bubbling green sludge pulse with an eerie glow, their surfaces rippling as occasional drips disturb them. High above, on the far side of the chamber, a massive black stalactite looms, its surface slick with rivulets of acid. Thin streams converge at its pointed tip before falling in steady, corrosive drops to the cavern floor below.   This chamber is the new home to an Adult Black Dragon (Glutandur, Venom Dragon stat block). The dragon is hiding on the Stalactite on the ceiling and will drop down and attack the party when a player moves within 20ft of the stalctite.
  • If a player succeeds on a DC 17 Perception check, they will notice

Character Creation

The copper mines of Biggarswith Hollow, hidden within the sprawling Planes of Alduun, have fallen into an unusual quiet. Once filled with the clatter of pickaxes and the hum of miner's songs, the tunnels now echo with nothing but still air. Shipments have ceased, and no word has come from the foreman or his crew. Tasked with uncovering the cause of this silence, you and your party are called to venture into the depths. But as the shadows deepen and the weight of the earth presses in, it becomes clear that something more than broken tools or fallen stone has halted the work below.   Edition: 5e
Level: 7
Stats: Point Buy
Gear: Starting gear plus your choice of 1x set of mundane armour
Magic Items: 5 Points + 1x +1 Weapon, Shield OR Armour
  • 1 Point - Potion of Healing
  • 2 Points - Uncommon Magic item
  • 3 Points - Rare Magic item

Resources

  Maps   Admin Level
Mining Level
Final Chamber
Items
  Stat Blocks  
  • Tithonoloth Tunneler
  • Tithonoloth Soldier Drone
Ankheg
Umber Hulk
Adult Black Dragon

DM Notes

  Background & Context
  • An Adult Black Dragon has moved into the mines and taken it over as its new layer
  • The black dragons activity in the region has caused a stir in a local colony of Tithonoloth, resulting in the colony dispersing and interupting minin operations of several of the regions mines
  • The foreman of Biggarswith hallow has been receiving correspondance from another nearby mines foreman, detailing strange occurances happening within their mine
  • As some of these occurences begin presenting in Biggarswith Hallow as well, the foreman investigates one of them deeper in the mines. During his investigation, the Tithonoloth arrive at Biggarswith Hallow as well, prompting the other miners to collapse several tunnels, including the one leading to the lower levels where the foreman went, in order to limit the space in the mines
  • Soon after, the dragon moved in, killed the miners and claimed the lower levels of the mine for his layer.
The adventure will lead the players through the mines where they will uncover this information VIA the foremans correspondance and a surviving miner.

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