Four colossal pillars of black volcanic stone rise from the sea, each soaring over a thousand feet into the air. Their jagged sides are riddled with sea caves and fissures, carved smooth by centuries of wind and wave. The ocean churns violently around their bases, breaking in white foam against the dark stone.

High above, seabirds circle the spires their cries lost to the endless wind. Few ships dare to sail near the Tyrants, for the waters here are treacherous, haunted by song and shadow alike.

Atmosphere

The sea around the Tyrants smells of salt, iron, and decay. The waves roar like voices in pain, and the constant wind carries faint, melodic notes that vanish when listened for directly.

To approach the Tyrants is to sail into myth and madness.

“The sea remembers every lover’s lie,” say the sailors, “and the Tyrants are her four black witnesses.”

Several Sea Harpies (1d4 + 2) make their home in the caves above the waterline. They emerge only at dusk or during storms, their luring song echoing across the waves.

• Luring Song: Each hour, roll 1d6; on a result of 6, one harpy begins to sing, even if no ship or creature is visible.

• The harpies rarely attack directly. Instead, they revel in watching ships founder and break apart on the rocks below.

• Local Legend: Sailors whisper that these harpies are the spirits of lovers betrayed cursed to sing others to ruin, reliving their heartbreak for eternity.

• On rare occasions, a harpy may be seen hunting seabirds. They seize gulls mid-flight, snap their necks, and drain their blood before dropping the lifeless bodies onto the decks of passing ships — a grim omen of what awaits.

Many caves open at or below the waterline, serving as lairs for the predators that feast on the drowned. The waters surrounding the Tyrants are infamous for their shark swarms and the eerie glow of pale eels that slither through the cracks in the stone.

When a ship sinks near the Tyrants, the sea itself seems to come alive — sharks circling the wreck, eels emerging from their holes, and somewhere below, vast tentacles stirring in the dark.

Creatures of the Tyrants

In 536 CY, the Royal Navy galleon Curiosity met her end upon the Tyrants. Drawn off course by the haunting songs of sea harpies, the vessel struck the black cliffs and was claimed by the crashing waves.

All hands were lost.

The wreck lies approximately 200 feet from the base of the Tyrants, resting intact upon the seabed at a depth of about 100 feet, her hull tilted slightly to starboard.

A great gash along the forward starboard side exposes the vast cargo hold, while the foredeck hatch gapes open above, offering a dim view into the darkness below.

Within the hold is the Apparatus of Kwalish.

It resembles a large, polished copper barrel, untouched by age. Upon closer inspection, faint seams and intricate runes trace its surface, hinting at hidden purpose. The hold around it is eerily barren, no coral, no barnacles, no sea life as though the device itself repels the sea and all that grows within it.

Encounters Near the Wreck

• Reef and Hunter Sharks patrol the waters above, hunting from the surface down to a depth of 50–60 feet.

• Giant White Eels lurk in the caves of the Tyrants, rarely venturing more than 200–300 feet from their lairs.

• A Giant Octopus occasionally drifts near the wreck, circling in the gloom, but it will not enter the ship’s hold as if wary of the copper machine that rests within.

Encounter in the Wreck

The Drowned Seraph (Abyssal Marilith) protects the wreck and will attack anyone that tries to enter the hull or mess with the Apparatus of Kwalish. (See statbloc and information below)

Resting in the Curiosity’s main cargo hold, the Apparatus of Kwalish appears to be a large sealed iron barrel weighing roughly 500 pounds. Despite decades underwater, it remains pristine no rust, no barnacles, no trace of decay.

Closer inspection reveals faint seams, delicate runes, and the whisper of intricate mechanisms beneath its shell.

Discovery

• A DC 20 Intelligence (Investigation) check reveals a hidden catch on one end.

• Releasing the catch unlocks a hatch large enough for two Medium or smaller creatures to crawl inside.

• Once the hatch is closed, the interior automatically flushes out water, creating a sealed, breathable chamber containing enough air for 10 hours, divided among those within.

Operation

Inside, ten brass levers line the forward control panel. Each lever rests in a neutral position and can be moved up or down.

• A creature can use an action to move up to two levers each round.

• After each use, a lever returns to its neutral position.

• To immediately understand the controls, a creature must succeed on a DC 18 Intelligence check; otherwise, the pilot must learn each lever through experimentation.
  

Statistics

The compartment is airtight and watertight when sealed. The Apparatus floats on water and can submerge at will.

Lever Functions

The Drowned Seraph (Abyssal Marilith)

Background

When the Curiosity sank, not all aboard perished. Among the crew was Ilyena Valhar, a gifted apprentice of Mordenkainen, entrusted with protecting the Apparatus of Kwalish.

As the vessel went down, Ilyena was consumed by despair, convinced she had failed her master and doomed his creation.

Her dying thought became an oath:

“I will not fail him again.”

In that moment of guilt and obsession, something in the deep answered. From the Endless Nadir, a haunted abyssal trench, shunned even by the aquatic races and said to be the site of a drowned aboleth city (see The Styes adventure), a dark power reached out.

Ilyena’s soul was dragged into that black abyss, reshaped by her own self-loathing and bound by the final threads of Mordenkainen’s warding magic.

What returned to guard the wreck was no longer human, a serpentine revenant infused with infernal grace and abyssal fury.

Behavior and Presence

Her voice still echoes through the wreck, carried by the cold currents of the deep:

“I failed him once… I will not fail again.”

When the adventurers approach the Curiosity, Ilyena immediately attacks any who near the Apparatus. However, invoking her name or Mordenkainen’s can momentarily break through her madness and allow fleeting moments of lucidity.

Dialogue Hooks

“His wards still burn in my veins. I cannot disobey… I will not fail again.”
“Tell me… is he still watching? Does he know what I became?”
“I hear him… in the currents… calling me home.”

Persuasion & Insight

• Speaking of Mordenkainen with reverence grants advantage on Charisma (Persuasion) checks.

• Mentioning her name can compel her to hesitate or obey a single command.

Redemption

If the adventurers find a way to redeem or release her, through Dispel Evil and Good, Greater Restoration, or intervention from Mordenkainen’s envoy, her body dissolves into pale light, and the sea around the wreck grows still.

Her final words echo faintly in the current:

“At last… I have not failed him…”

Notes:

• Fireborn's Naval Book Clue:
  The entry mentions an apprentice named: Ilyena Valhar servant to Mordendkainen.

• Envoy: If the party meets the Envoy prior to visiting the wreck, he will mention that Mordenkainen's apprentice, Ilyena Valhar perished in the wreck and it has weighted on Mordenkainen's heart ever since.

• If Redeemed: The envoy personally thanks the adventurers and grants an additional boon (DM's discretion):

“Few souls find peace after such torment. You have done what even the Circle could not.”

Statbloc & Lore

Use the Marilith stat block with the following modifications:

Type: Fiend (formerly humanoid)
Alignment: Lawful Neutral (driven by duty, not malice)
HP: 180

Special Traits:

• Echo of Mortality. When reduced below 50 HP, Ilyena partially reverts to her human form, her voice trembling as she begs forgiveness.

• Bound by Oath. She cannot move more than 60 ft. from the Apparatus.

• Abyssal Warden. If Mordenkainen’s name is spoken, she must succeed on a DC 17 Wisdom save or lose her next action, overcome by memory and conflict.