This adventure follows the events of Fate of the Sun Siren Beacon (in which Rook Varlo escapes with the Sun Siren Beacon) the stakes are clearly defined, so it is easily run as a standalone boss-lair one-shot, perfect if your players have a gallery of combat-hungry characters. This article also recycles some of the fantastic monsters used in the Graven Grotto article by Troy. 

Adventure Background

Trade has quietened around Prizewater. The town still lives by whatever the sea coughs up, but now the coastline feels watched, like something out there has learned the town’s habits and is daring it to blink first. Locals whisper about nights where the water flashes with a steady “second dawn,” a pale glow on the horizon that turns waves to glass and draws hungry shapes toward shore.

The Sun Siren Beacon can conjure bright sunlight within a region, but each use stirs the sea—calling predators, scavengers, and worse. A druid named Rook has abused the artefact’s ability to summon sea monsters to control trade along this part of the coast, causing ships to wreck in favourable areas where his Sand Bandits can quickly loot goods and trade further inland.

The Beacon’s power has answered with a curse: Rook is becoming a wretched aberration, his body reshaped by radiant heat and deep-sea hunger. Worse still, the Sand Bandits are changing with him.

Notable NPCs

Sister Maris of the Lucent Maiden

Role: Resident priest of Prizewater

Appearance: Young human priest with wind-tangled brown hair, travel-stained robes in pale blues and whites, and a simple golden holy symbol of the Lucent Maiden.

Personality: Earnest, soft-spoken, and a little overwhelmed by politics. Steady in a storm, but more comfortable with small, honest conversations than grand speeches.

Motivation: Keep the Sun Siren Beacon in the hands of the Church of the Lucent Maiden and ensure it’s used only to protect and guide those in danger at sea.

Maris (F Human Priest) serves as the resident priest of the Tide-Bell Shrine. Her duties are simple: tend the bell, bless departing boats, and pray that the Lucent Maiden guides strangers safely past the reefs. She’s grown up with stories of the Sun Siren Beacon, a relic of her faith said to clear storm clouds and conjure bright sunlight within a mile radius, turning night into day and fog into clear sky. She also knows the dangerous side: every use stirs the sea and calls creatures from the depths, drawn to the sudden light and warmth.

Earnest, shaken, and furious in a quiet way. She wants the beacon returned to the church of the Lucent Maiden, so she equips the characters with supplies to defeat the monsters that threaten Prizewater.

Farik (The Fading Bandit)

Role: The last bit of humanity in the Sand Bandits, a hint at what the characters will face on this quest.

Appearance: His eyes are colourless, with one eye bulging more than the other. Parts of his skin look like kelp, and some of his teeth are hooked.

Personality: Short-breathed, desperate, and regretful.

Motivation: Seeks help from anyone to stop Rook from going too far and taking the Sand Bandits along on his spiral.

Farik is on the verge of transformation into a marine monstrosity. Long ago, escaping the cells of Prizewater, he now returns in the cover of night and finds refuge with Sister Maris. He shares a map leading to Driftwood Cove and says Rook plans to summon sea monsters to assault Prizewater. After sharing the map and the plans, Farik transforms into an Ocean-Grafted Ghoul (Anglerfish-Eel)

Mayor Carina Rowley

Role: Elected town official.

Appearance: Early-forties human woman with sun-browned skin, dark hair threaded with grey and tied back in a scarf, and a weather-beaten sailor’s coat worn over a neat mayoral sash.

Personality: Steady, sharp-eyed, and dryly humorous. Carina listens more than she speaks and hates wasted opportunities. She genuinely cares about Prizewater but is fiercely protective of her authority.

Motivation: Keep the Sun Siren Beacon out of the Sand Bandits’ hands, prevent the priests from gaining too much leverage over the town, and quietly turn the relic into coin and political favour via the black market.

Carina (F Human Noble) grew up in Prizewater as the child of wreck-pickers and clawed her way into leadership by keeping the town alive through lean years.

Adventure Setup

Tide-Bell Shrine is where Prizewater’s problems get solved in public. Inside is a notice board of council decisions, beside offering bowls, a cramped cot-lined corner that serves as the town’s medical space, and the low thrum of argument from the adjacent offices. The town’s murmured tension between law and religion is a living thing here, especially when miracles are involved.

Sister Maris summons the characters to Tide-Bell Shrine after Farik seeks refuge with the priest. She introduces Farik as a man who once called Prizewater home before he was arrested for burglary. He’s barely conscious, fever-bright, and wrong—skin tight like sun-dried kelp, teeth hooked, eyes milky. 

Though he struggles to speak through his hooked teeth and shortened breaths, Farik admits regret for the greed that took him on this cursed path with the Sand bandits. He pleads with the characters to stop Rook and offers a map to Driftwood Cove, along with the following information:

• Rook is obsessive over the beacon and refuses to part with it. It has transformed him into a shelled monstrosity with crab claws and tentacles. 
• Rook uses the beacon to summon creatures from the deep and can turn seawater into acid. 
• The rest of the Sand Bandits have lost their bodies and minds and follow Rook’s every command. 

Before Farik can say much more, Mayor Carina Rowley (Noble) arrives.

Carina’s aim isn’t to arrest Maris or seize Farik on the spot. She’s too careful for that. She’s here to ensure the party understands the stakes are political as well as monstrous: whoever controls the Beacon controls whether the town prospers, who holds leverage, and who gets blamed when things go wrong. 

As Farik hands the map over, he completely transforms into an Ocean-Grafted Ghoul (Anglerfish-Eel) and attacks until killed. While he is hostile, Sister Maris and Mayor Carina focus on keeping other civilians in the shrine safe. A Remove Curse spell will revert him to his human form. 

After killing Farik, Sister Maris stresses that this is a threat that needs to be dealt with immediately. She equips the characters with 2 Potions of Greater Healing, 1 Ring of Water Walking, 1 Ring of Swimming, and a Potion of Heroism. Sister Maris promises that the Church of the Lucent Maiden will reward them with free divine services for a year if they bring the Beacon back to the church. 

The Mayor’s Offer

Mayor Carina shows the characters out and waits until they’re out of earshot from the shrine, where she makes her own offer to the characters. She wants the Beacon secured for the town’s safety. Kept out of Sand Bandit hands and out of the church’s. Unofficially, her meaning is clear: control. If the priests claim it, they gain leverage; Carina would rather turn it into coin, supplies, and favours through contacts inland. She offers a generous 500 gp if the beacon is given to her.

Driftwood Cove

With Farik’s map on hand, finding Driftwood Cove is no challenge to the characters. The cove is hidden by cliffs riddled with spherical boulders uncommon to the rest of the coast. Old Sand Bandit markers hang from ropes: shells, bones, driftwood charms. Now they’ve been “improved” with sunburst carvings and strips of kelp that twitch like living things.

Wet sand gleams under a pale light that doesn’t come from the sun–like a supernatural spotlight. Driftwood and ship debris lie scattered like picked bones while shambling figures wander the cove, swaying to the chanting that echoes from a cave mouth.

Lumbering through shallow waters are the monstrosities that were once the Sand Bandits. The sea has taken their body and soul. Rook uses the cave to amplify his summoning of sea monsters.

General Features

Rook and the Sand Bandits use this cove to their advantage. The monsters they’ve become easily wade through the waters, and since the cove opens to the sea, Rook summons more sea monsters with ease.

Shallow Waters. The tide draws in a depth of 3 feet. Enough to make the water in this cove difficult terrain for any creature without a swimming speed. 

Slick Rocks. The rocks are slick and slimy, making them difficult to climb unless a creature succeeds on a DC 15 Athletics (Strength) check. Debris & Driftwood. The driftwood that litters the cove has piled up enough for three-quarters cover for a medium-sized creature.

What is Happening?

Rook is calling upon the deep ocean to unleash a wrath of sea monsters upon the land, while the monstrous Sand Bandits sway to his chanting. Characters arriving at the scene won’t see Rook unless they enter the cave or he is drawn out of it. While the Sand Bandits are focused on the chanting from the cave, the characters may attempt to sneak up on them with a successful DC 15 Stealth (Dexterity) check. The characters may also wish to scale down from the cliffs above to avoid entering the cove, but doing so requires a DC 15 Athletics (Strength) check and makes it impossible to naturally hide from other creatures of the cove.

The Monsters

Rook in his Lair

Beacon-Cursed Rook

CR 4

The Beacon’s influence on Rook has merged the druid’s body with sea creatures. Patches of his skin have turned chitinous, his hands have transformed into pincers, and tentacles emerge from beneath his ribs.

While Rook is in the cove and possesses the Sun Siren beacon, he may activate one of the following lair actions on initiative 20 (losing ties).

Water to Acid. Until Rook uses another lair action, creatures without a swim speed who start their turn in the water take 2 (1d4) Acid damage.

Burning Sands.  Until Rook uses another lair action, creatures who start their turn on dry sand take 3 (1d6) fire damage.

Undertow. All creatures in the cove water without a swim speed must succeed on a DC 15 Strength saving throw or fall prone. Calling the Sea. 2 Ocean-Grafted Ghouls emerge from the ocean and join combat.

Defeating Rook

Rook doesn’t go down without a fight. A character taking the beacon from his hands removes his control of the environment, but marks them as a target for all the marine monstrosities. If Rook is killed, all Ocean-Grafted Ghouls trundle back to the depths of the ocean.

Completing the Call

If the characters are defeated by Rook, they join Rook’s monstrous army and march onto Prizewater, where they bring chaos upon the town they swore to protect.

Conclusion

With Rook defeated, the worst of the coastal threat recedes. Back in Prizewater, the roads feel safer within days, but safety is not the same as peace. The town has tasted what it means to be chosen by an artefact, and now two hands reach for its power

If Sister Maris Claims the Beacon

Sister Maris insists the Sun Siren Beacon cannot remain in Prizewater. She prepares to carry it inland to the nearest city, to place it under senior wards of the Church of the Lucent Maiden. If the characters travel with her, the journey becomes a pilgrimage under threat: lonely cliff-roads, night camps lit by wary firelight, and the constant fear that even a wrapped, silent relic might call hungry shapes from the surf.

If Mayor Carina Claims the Beacon

Mayor Carina Rowley moves fast, praising the characters loudly enough to steady the town. The beacon becomes a bargaining chip—packed into an unmarked crate, and quietly routed toward inland contacts who can turn it into coin, supplies, and favours that keep Prizewater hers, and out of the church’s control. If the characters aid her, they may be paid in salvage rights and influence, but they also inherit the secrecy.

Support the Creators

Ian Arguilles
What do Ian, a hydra, and a hat rack have in common? They all wear many hats. Ian freelances across copywriting, short fiction, and RPG design. If you’d rather just hear him ramble about telling better stories at the table, look for Unfound Fables on Instagram.

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