Primordial Waters#

The Nether Sea is dangerous for many reasons, but the water itself is the most immediate risk. For one thing, the waters are acidic, and each day, they inflict 30 damage to the ship’s hull. The Ultros has been magically protected from the waters of the Nether Sea, so it only takes 5 Acid damage per day.

Primordial Whales#

Massive, whale-like creatures sometimes surface in the Nether Sea. Ships that draw too close to them risk capsizing in their wake. These gargantuan beasts don’t react to attacks unless they take more than 100 damage, and then they simply submerge beneath the waters once more. The whale creatures have AC 22 and are immune to most conditions: Blinded, Charmed, Frightened, Paralyzed, and Poisoned. They have unlimited uses of Legendary Resistance.

Drinking the Water#

Anyone who drinks the seawater or submerges themselves are immediately affected by the warping effects of the cosmic matter. Roll on the Effects of the Primordial Waters table. The first time someone interacts with the water, the effects wear off after one hour. The second time they touch the water, the effects last one day. The third time, the effects become permanent. Re-roll the effect each time.

Estor Arkelander#

Once the heroes enter the Nether Sea, Estor reveals himself and presses them to seek the Mirror Prison. He speaks of ancient weapons hidden there, and insists that without such power, Lutheria cannot be slain. If questioned about the Mirror Prison, Estor lies without hesitation. He claims it is a vault where the titans imprisoned weapons they feared.

Leaving the Nether Sea#

Leaving the Nether Sea is easier than getting here. The Charybdis whirlpool is the most obvious way to leave. Ships that sail into Charybdis from the Nether Sea will defy physics and sail upwards to the roof of the enormous cavern. The ship emerges a few miles from the whirlpool on the surface of the Cerulean Gulf.

Control Water#

The Control Water spell can also be used to leave the Nether Sea. If cast upon the primordial waters, the effects will be much different than if it had been cast on the surface. Instead of creating a whirlpool, the spell will create a massive spout of water. Effectively, the spell can be used to create a temporary Charybdis at any location in the Nether Sea.

Nether Sea Key Locations#

N1: Charybdis#

Just ahead, the Nether Sea breaks into a churning maelstrom of incomprehensible height. Primordial waters churn and gush thousands of feet into the air, vanishing into the darkness of the sky above.

This is an inverted whirlpool known as Charybdis. Sailing into it will deposit a ship on the surface of the Forgotten Sea, a few miles away from the gargantuan whirlpool. There is, however, a 5% chance that any ship entering Charybdis will be utterly annihilated by the cosmic forces that power it. In this case, the crew will find themselves clinging to wreckage in the Cerulean Gulf. Depending on their actions as the ship is swept upwards, they may be able to salvage their equipment.

Nyxian Heroes A hero of the Nyxian species is completely immune to the warping effects of the Nether Sea. In addition, they have Advantage on all saving throws and ability checks made while exploring the Nether Sea.
Full-page art, p.147
Full-page art — p.147

N2: The River Lethe#

Your vessel drifts towards what appears to be a heavy rain storm. Strangely, no strong winds can be felt and the nearby waves remain calm. The “storm” does not seem to move. It remains in one place and seems to be confined to a narrow area. The falling rain smells fresh, and lacks the acidic odor of the surrounding waters.

The River Lethe falls from the ceiling of the Nether Sea cavern above, starting from the Dead Falls. By this point, it is like torrential freshwater rain.

Lutheria sails into this constant rainstorm every day so that she can keep her gardens properly watered. Therefore, staying close to the River Lethe’s falls is an excellent way to find and confront Lutheria. See Lutheria’s Barge at the end of this section for details.

N3: Titan Island#

Your ship approaches a small craggy island dominated by gray mountains and black, rocky beaches. Among the mountains stand three incredibly lifelike statues which are similar in scale to the great colossi of Mytros. Each depicts a muscular man in a pose suggesting shock, their faces revealing a combination of fear and rage. Iron chains bind their immobile limbs and are anchored in the surrounding landscape.

Three ancient Titans are petrified on this island. They are siblings of Sydon and Lutheria, and all three tower to 50 feet in height. Two of them are entirely inert, but one still has the ability to speak. If this statue is approached, its eyes open and its head turns slightly toward whoever has come near. Dust rains down as it strains against the magic that petrifies its body.

The speaking titan is quite mad and doesn’t even remember its name, although it knows that it was betrayed and trapped by Sydon and Lutheria. It also knows a few secrets that could be used against Sydon or Lutheria:

  • Lutheria is insane. Sydon once tried to cure his sister by forging weapons from the psychic energy of her madness (Hall of Armaments, area H6). These weapons may be especially effective against her.

  • Lutheria has a warped sense of humor. She likes to tell jokes. She sews your mouth shut if you don’t laugh at her jokes. It’s always better to laugh at her jokes.

  • Lutheria loves to play games. She especially loves the Royal Game (the Game of Twenty Squares, appendix C). Challenging her to the game can put her in a better mood, but you should always let her win.

  • Lutheria roams the Nether Sea. Lutheria’s barge is almost impossible to find unless she chooses to reveal

herself to you. However, she takes an interest in any threat to her domain. For example, the Gargantuan Cubes (area N6) are prisons for powerful weapons. If the heroes can awaken one of the imprisoned weapons, the noise would echo across the entire Nether Sea and summon Lutheria to them. The Titan knows the word that unlocks The Prison Cube. He will whisper this almost unpronounceable primordial word to anyone who asks him for it. Whoever hears the word gains a random short-term mental stress (see the Game Master’s Guide), but they cannot say the word until they stand before the locked entrance. The word remains in their mind until they speak it, and then they will forget it.

  • The waters of the Nether Sea are strange. One must be cautious with the waters here. Spells that manipulate water, such as Control Water, may have unpredictable effects.

N4: The Mirror Prison#

Dim lights dance upon the horizon. As your ship moves closer, you discover their source: an immense, partially submerged crystalline structure reflects the strange light of this strange place. Countless flat panels connect at strange angles, creating a vaguely pyramid shape. Near the waterline is a gaping hole large enough to allow passage by the Ultros . Jagged edges suggest that this entryway was made by force rather than being an original feature of this odd structure.

This huge crystal structure rises out of the Nether Sea. The Kraken was once imprisoned here, but it escaped and now dwells in the Forgotten Sea. A gaping hole near the water line allows access into the interior of the mirror prison. A ship such as the Ultros can sail into this hole to the interior of the crystal structure.

The walls and ceiling of the interior are covered in hundreds of square mirrors, each 6 feet to a side. These mirrors reflect whoever enters the prison, and each mirror shows a warped version of the viewer. At the rear of the crystal structure’s interior is a small island made from broken mirrors. Gold, silver, and gemstones are piled on the island in a large hoard.

The Dragon’s Lair. This island is the lair of a Chaotic Evil Adult Brass Dragon named Hezzebal. Hezzebal was the mount of a Dragonlord who explored the Nether Sea five centuries ago, scouting for a location to hide the treasures of the Dragonlords. Hezzebal broke into the Mirror Prison and accidentally released the Kraken in the process. The Kraken sealed the dragon inside the prison and then tormented him by slowly and messily devouring his bonded Dragonlord.

Over centuries, the mirrors warped Hezzebal so that his wings became twisted, and his alignment has changed to evil. Hezzebal now lairs in the broken prison, occasionally going out into the Nether Sea to hunt.

Hezzebal usually lurks beneath the water, having become immune to the effects of the Nether Sea. He will surface to converse with intruders if they start to loot his dragon hoard. He will reveal his history to gain sympathy and will inquire about the party’s purpose here.

“You,” he growls, voice echoing through the mirror-lined chamber. “My jailers return at last.” Cracks of rage tremble along his warped wings. “You left me here. You abandoned us all. Dragons were never brothers to you Dragonlords. We were merely steeds to ride and cast aside.” His voice rises into a trembling roar. “I rotted while you vanished into legend!”

At this point, Hezzebal will attack. Refer to Battling Hezzebal section.

If the Vanished One is Not Present. If the heroes reveal that they are enemies of Lutheria, then Hezzebal explains that she is a vain creature. She visits the River Lethe with some frequency, in order to water her gardens. He has always kept his distance from her. Eventually, Hezzebal will grow bored of talking and will try to devour the heroes.

Battling Hezzebal. Hezzebal cannot fly. He has a Swim Speed of 80 feet, he is immune to the effects of the Nether Sea, and he has Water Breathing. His madness can be cured with a Greater Restoration spell, but it must be cast three times, and he will interpret it as a hostile action. If his madness is cured, his alignment reverts to good, but he has three permanent levels of Exhaustion.

The Mirrors. Use the Mirror’s Effect table to randomly determine what someone sees upon looking into a mirror. Once someone has looked into a mirror, it may be removed from the wall and taken away for use elsewhere, but doing so requires a successful DC 20 Dexterity check. Otherwise, the mirror will shatter when it is taken down.

If someone looks at one of the mirrors for an entire round, they must succeed on a DC 20 Wisdom saving throw or be transformed into the form of their reflection. This can be reversed with a Greater Restoration spell.

The Dragon’s Hoard. The dragon’s hoard consists of 30,000 SP, 5,000 GP, and a single adamantine ingot. Buried deep beneath the heaps of coin lies the Xiphos of Slaughter (appendix C). This blade was once the favored weapon of Estor Arkelander, wrested from him by the Dragonlord bonded to Hezzebal at Xander’s command. Xander believed that separating Estor from the dagger would temper his bloodlust. It did not.

Estor Arkelander. If Estor Arkelander is aboard the Ultros, then read the following:

A chill rolls through the air, and Estor Arkelander manifests beside you, his spectral form coalescing like smoke into shape. His eyes burn with triumph. He points a spectral finger toward a dagger with a golden hilt gleaming upon the hoard. “That blade answers to my hand.”

Estor refuses to part with the Xiphos of Slaughter (appendix C).

“Our bargain stands,” he intones. “One treasure was promised to me, now you can claim the treasure promised to you.”

The Lost One should choose the items that they want from the list of possible rewards for their epic background. The other items from the list are not present. Refer to the Lost One section in appendix G of The Great Labors for details.

N5: Island of the Oathbreakers#

A small, rocky island rises from the inky black sea. From a distance, its surface appears to be covered by a forest of twisted, leafless trees that begins near the waterline. Closer inspection reveals that the trees are petrified, made from the same dark gray stone as the rest of the island. A great column of the same stone rises high above their tallest branches at the forest’s center.

This island is where all oathbreakers from Thylea are brought by Lutheria’s Erinyes. It is a place of punishment for any who break solemnly-sworn oaths, and rightly held to be a terrible place by all mortals.

Many centuries ago, when mortals first began to arrive on the shores of Thylea, Lutheria made a deal with a

nalfeshnee native to Hades. This nalfeshnee became the warden of the prisoners brought to the Island of the Oathbreakers. When an erinyes arrives with an oathbreaker, the Nalfeshnee chains the offender to the central column and threatens torture as punishment for attempting to escape.

The Oathbreakers. The island is surrounded by an entropic field which sustains prisoners, eliminating the need for them to eat or drink, although they are perpetually hungry and thirsty. There are hundreds of mortals still alive on the island and thousands of corpses, some centuries dead. Every one of these prisoners is chained to the central column that rises from the center of the island.

As you approach the center of the island, you are able to make out the thousands of individual chains anchored in the great stone pillar. Held fast by the chains are the skeletal remains of many mortals. Some appear to be centuries old. Although there are some living prisoners, they ignore you. Most of them seem to have had their mouths sewn shut.

The nalfeshnee keeps the prisoners alive until they perish of natural causes. He is served by two Hezrou who watch the prisoners intently and occasionally torment them for their own amusement.

Lutheria’s Punishment. The vast majority of the prisoners here have had their mouths sewn shut. However, this is not the nalfeshnee’s handiwork. Every year, Lutheria visits the island and tells jokes to the prisoners, making a note of those who do not laugh loudly enough. Then, she personally sews their mouths shut as punishment.

The Wisest Prisoner. The most helpful prisoner on the island is a woman named Oresteia (NE Mage). Oresteia is one of very few prisoners who can speak, because she’s wise enough to flatter the Lady of Dreams during her annual visits. Oresteia has two pieces of advice for the heroes:

Š Always laugh at Lutheria’s jokes.

Š Challenge Lutheria to the Royal Game.

Oresteia has earned preferential treatment from the Lady of Dreams for decades by following this advice. She keeps the Titan entertained by humoring her jokes and devising surprising new strategies for the Royal Game. Lutheria has even ordered the nalfeshnee to keep the Mage in some measure of comfort, bringing her wine and stale bread from time to time.

Oresteia warns the heroes that Lutheria will always win the Game of Twenty Squares (appendix C), because she’s devised some way to cheat. The Titan loves winning almost as much as she hates losing. However, the magic she uses to cheat at the game also seems to drain her energy. The Mage has never pushed her luck enough to try and win the game, but it’s possible that Lutheria will be more vulnerable after a particularly rousing game.

N6: Prison of the Tarrasque#

Your vessel sails towards an island that seems strangely square-shaped. It soon becomes clear that the island is actually a gargantuan iron cube. Runes have been deeply etched into each of the faces you can see. The bottom face is level with the surface of the sea; the top face, some hundred feet above, hangs from five massive chains. The chains disappear into the fathomless heavens of the Nether Sea. A disturbing noise echoes from within the structure, alternating between a low rumble and a high whistle.

A huge iron cube, 200 feet on each edge, hangs from five massive chains: four chains attach to the top corners of the cube, and the last attaches to the center of the cube’s top face. The bottom of the cube just touches the water of the Nether Sea. There are runes inscribed into the iron cube, and these can be used as handholds if anyone tries to climb the walls. The top face of the iron cube is flat except for a small entryway in one corner (area B1).

The cube that hangs closest to Titan Island (area N3) is the only cube that the heroes are able to gain access to. They must have learned the primordial word from the living Titan on that island in order to enter it.

N7: Prison of the Nether Dragon#

This enormous cube contains the Nether Dragon (appendix B). Refer to chapter 10 for more details. It has no keeper, for it has no need for sustenance.

N8: Prison of the Behemoth#

This enormous cube contains the Behemoth (appendix B). Refer to chapter 10 for more details. Its keeper is Aetherion, a Planetar who often visited the lands of Thylea. During one of his visits, he fell in love with Versi, the Oracle. When the Three Fates foretold that the Behemoth would one day devour Versi unless stopped by one she loved, Aetherion believed the prophecy spoke of him.

To save her, he descended willingly into the Nether Sea, offering to guard the monster for all eternity. But the Fates are cruel. Versi never loved him, and the prophecy did not concern him at all. It concerned the Heroes of the Prophecy.

N9: Broken Prison#

Your vessel drifts toward an island that isn’t an island at all, but a colossal iron cube. Each face is carved with deep, ancient runes. The top hangs suspended by five vast chains that vanish into the black heavens of the Nether Sea. The cube’s bottom edge cuts the water’s surface cleanly; yet it is split open, torn apart from within. Whatever was contained inside, ripped its way out.

Whatever powerful titan was contained in this prison escaped millennia ago.

N10: Prison of the Twin#

This final cube holds the titan Ariadne (Hyperion, appendix B). She is the sister of the Behemoth. (See chapter 10 for details.) Her keeper is Sisyphus, a Mummy Lord who was once a proud Gygan emperor. In life, he sought power beyond the reach of mortals and struck a bargain with Lutheria: he would serve her faithfully until his dying breath, and in return she would grant him dominion and strength unrivaled among kings. When his final hour came, Lutheria appeared beside his deathbed. She plunged her hand into his chest and tore out his heart, whispering that his breath would never end. His body rose again as an undead husk, cursed to serve forever. His hidden heart still beats somewhere in the Nether Sea, binding him to his endless vigil as the Titan’s warden.

Ariadne can become an ally against the Behemoth in chapter 10.

Lutheria’s Barge#

A movement on the horizon breaks the gloomy monotony of the Nether Sea. A pair of immense shapes come into view: the first is the upper body of a colossal male humanoid wading through the waves. Rags obscure much of his face, but it is clear that his lips have been sealed shut. Scars cover his muscular body as he trudges slowly onward, gripping onto a great length of chain. He pulls a massive, impressive bronze barge. Lush green plants spill over the top of the barge—a verdant garden in a lifeless expanse of black ocean.

This barge is the Hypnos, the dwelling place of Lutheria. This massive bronze vessel is pulled by Talieus (LN Hyperion, appendix B), a 200-foot-tall Titan who has been blinded and broken by his malevolent sister. He wades through the Nether Sea, eternally pulling Lutheria’s barge.

Lutheria’s barge is a hanging garden that features lush plants, vines, and trees. Fantastical flowers grow in the garden, of almost every kind imaginable, and their perfume almost drowns out the acidic smell of the Nether Sea. If the heroes approach Lutheria’s barge, refer to the Hypnos, Throne of Dreams section.

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