This adventuring supplement is designed for D&D5e. On out Patreon page you can get it in PDF format (see image). The downloads include hi-res images for the maps. And there is a variant PDF version designed for Shadowdark RPG.
“Extraplanar, fiery rage flows through my core. Wield my strength and be a witness of a conflagration that shall cleanse your enemies from this world.”
Voice of the Magma Hammer
These ancient halls were built by dwarves thousands of years ago. Once, the dungeon was connected to a great city in the Underdark but the tunnels were destroyed eons ago. The Vault of Molten Stone is a forge that commands the elemental power of a volcano. The forge chamber is so hot that heat protection is required. Dwarf craftsmen used it to create peerless marvels. One of these relics of great power is the Magma Hammer; a weapon and forging tool made of red-hot stone that never cools down.
Dwarves have not visited this place recently. Some daring explorers have delved into the first chambers but found their resolve broken by the inclement heat and the deadly traps and guardians. Another secret of great relevance lies hidden in a treasure room (area 11): a scroll that depicts a forlorn ritual capable of appeasing the Avatar of the Sea, the sahuagin goddess, and bringing peace.
Adventure Hooks
The Hammer. The high priest of Saravenna’s Chapel of Fire offers a hefty reward for retrieving the Magma Hammer said to be hidden herein. The high priest claims this relic belongs to the church (400 gp).
Royal Agents. Prince Daelin from Onyx Keep believes this dungeon holds a truth with the power to stop the sahuagin without using force. He wishes for the hammer to stay away from Saravena’s troops, who only want war. He is interested in a magical means to accelerate the ancestral event affecting the sahuagin.
Level 4 Dungeon
- Danger. Risky. Check for a Random Event every 20 minutes and after loud noises (4-in-6 chance).
- Light. Most areas are dimly lit by the lava; unless the flow is stopped. All denizens have darkvision.
- Heat. Creatures within 5 feet of a lava canal take 1d6 damage every 10 minutes. This effect can be ignored if magic or special attire is used. The heat in area 9 is too intense to bear without magic. Stopping the lava flow in areas 7 and 8 lowers the heat enough to enter.
| RANDOM EVENT d6 | Details |
| 1 | A salamander emerges from a nearby lava canal and attacks non-dwarves. It flees if reduced to half its Hit Points. |
| 2 | Lava flows harder, the canals overflow, and lava pours onto the floor. The characters must quickly avoid it (DC 14 Dexterity / 2d6 damage). Lava outside of the canals disappears at dawn. If the lava flow was staunched, it returns to its normal flow rate. |
| 3 | A lava bubble in the canal bursts. Creatures within 15 feet take 2d8 damage (DC 13 Dexterity save for half). |
| 4 | Spectral apparitions of dwarven blacksmiths can be seen walking toward an anvil and hammering at a piece of metal. The only sound carried through the ether is the hammer as it hits true. The visions disappear after 10 minutes. |
| 5 | A hidden pressure plate triggers a thrusting spear trap. A random hero takes 1d10 unless they jump aside (DC 14 Dexterity). |
| 6 | A sudden burst of heat and sparks sets on fire a random object worn or carried by the party. |
1. Antechamber
Several lava canals converge here, flanking the central circle and passing by skull-littered shelves.
- The Skulls. Dwarven skulls of renowned craftsmen are on display here; their names etched on the bone.
- The Vases. The gilded vases by the back wall contain black flammable powder. If packed tightly, it can be used to improvise an exploding device (DC 13 Arcana).
2. The Archive
The tomes and scrolls in this chamber keep an accurate, time-resistant log of dwarven blacksmiths and their metalwork creations in the Great Forge (area 9).
- Floor Plan. Exploring the archive for 10 minutes reveals a detailed plan of the dungeon. The characters learn of the secret rooms and gain insight into the working of the flow valves in areas 7 and 8. Learning this provides advantage in operating those valves. It also reveals the presence of the fire elemental in area 9.
- Lost Lore. Four tomes with secret forging techniques known only by dwarf artisans can be sold to the blacksmith, Amman, in Saravenna for 350 gp.
3. East Room of Materials
While symmetrical and orderly, this is a storage room. The large vases contain coal and burning powder. The large coffer contains iron and copper ingots.
- Blade Trap. A deadly device is triggered when the door to area 3 is opened. The blade swings inward and deals 4d6 damage to whoever stands on the threshold (DC 14 Dexterity save for half). Lethal damage dealt by this trap results in the disembowelment of the target.
- Treasure. The stone coffer contains one thousand ingots; most of them iron. Together, the ingots weigh close to 6 tons. The ingots can be sold wholesale in the principalities for 800 gp over a period of 3 months.
4. The Library
This chamber contains a collection of poetry, fiction, legends, and dwarven architecture tomes. A log on the desk records recent readings. The most recent entry dates back to 850 years and lists a dwarven family name.
- Arcane Lore. Inspecting the library documents for 10 minutes disturbs the eternal rest of three undead shadows; they fight until destroyed. In the reviewed documents, but cleverly hidden in plain sight in a children’s storybook inscriptions, there are three Wizard spells: sleep, detect thoughts, and hold person.
5. West Room of Materials
This chamber is similar to area 3 but the containers and ingot coffer are empty. A ghastly figure floats near the stone container; the remnant of a dwarven artisan.
- The Spirit. The ghost of Dirk Barkilli, a dwarf blacksmith, introduces himself to the party. He yearns to practice his craft once more but can only do so with the characters’ help. Dirk confers one person the ability to resist all heat damage. If the characters agree to help, they must bring his etched skull from area 1 to area 9, attach it to the Magma Hammer, bring an ingot from area 3 and heat in the Great Forge, and hammer out its impurities. Then, Dirk gifts them a scarab of protection.
6. Black Powder Factory
The machines in these rooms process the lava to create a fine, powdery substance that burns explosively when exposed to fire. When compacted in containers, it can be used to create explosive devices. Two such barreled explosives lie by the wall. If set off, all creatures within 15 feet take 6d6 damage (DC 13 Dexterity save). The machinery in the room can be used to produce enough powder for another barrel (DC 16 Intelligence).
7. East Control Room
This chamber contains four valves that can be used to staunch the Great Forge’s lava flow (DC 12 Intelligence). 1 crawling round after using them, the temperature in area 9 equals that of the rest of the dungeon chambers.
- Secret Door. In the alcove, opening the goblet lid reveals a hidden pathway to area 10 (DC 13 Perception).
8. West Control Room
This chamber is similar to area 7 but the valves are rusted and corroded. There are also half-consumed remnants of iron ingots strewn across the stone floor.
- The Oozes. Five gray oozes, guilty of consuming the materials in area 5 and destroying the machinery here, cling to the ceiling. They drop in response to sound.
- Secret Door. In the alcove, opening the goblet lid reveals a hidden pathway to area 11 (DC 13 Perception).
9. The Great Forge
A 30-foot-tall, ominous-looking visage pours an endless flow of molten stone from its maw. It is the face of a mystical djinni, a primordial fire-based entity. Black anvils before the forge mark the place where countless craftsmen created marvelous trinkets.
- The Caskets. Seven ornate sarcophagi line the walls of this chamber. Each lid features a fist-sized ruby (50 gp each). When the characters come within 10 feet of an anvil, all lids slide aside. Seven skeletons emerge from the caskets to attack. The undead fight until slain.
- The Anvils. The three anvils are crafted from a strange, iridescent alloy. Their unbound hardness is the secret to many dwarven creations. Coming within 10 feet of the Great Forge causes a fire elemental to emerge from the lava. If the lava flow has been staunched in area 7, the elemental has 40 fewer Hit Points.
- The Forge. Beyond the djinni’s decorative mask lies a magical kiln connected to the heart of a volcano. The forge’s temperature is reduced for 10 minutes after defeating the fire elemental. It is possible to retrieve the Magma Hammer from within the forge’s kiln then.
- In the flaming depths of the forge’s kiln lies the Magma Hammer, a weapon without parallel.
10. East Vault
The room contains four stone chests arranged by the walls. Each brandishes an ancient dwarven clan rune.
- Treasure. The coffers contain 250 gp, 1,200 sp, two potions of healing, and three flasks of oil.
- West Vault
The room contains three empty chests and two bookshelves packed to the brim with tomes and scrolls.
- The Ritual. Studying the documents in this chamber reveals a ritual with the power to appease the Avatar of the Sea, the sahuagin goddess. A spellcaster must study these documents for 1 day to learn it. It was stored here by dwarves to work at the forge during the 10-year period during which the avatar appears.
The Magma Hammer
A warhammer of incandescent, molten stone that keeps its modest shape while radiating inclement heat.
Bonus. +2 sentient warhammer.
Benefit. Once per day, you can cause an explosion upon dealing a successful hit. Creatures within 10 feet (except you), take 4d6 damage (DC 14 Dexterity for half).
Epic Slayer. Immortal beings can be slain with this weapon as it bypasses their otherworldly nature.
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