The Sunken Oath
The Sunken Oath
An estranged warlock and cleric are drawn back together by cryptic summons to a flooded temple in the Sword Coast, where their shared past—and a pact neither fully remembers—demands blood payment. The cleric's sister, a monk, tags along to protect her sibling, only to discover that something older than memory hungers in the dark waters below.
Read Aloud
Rain slicks the earth as you push through the forest northwest of Waterdeep, drawn by identical parchments that arrived within days of each other—written in a hand none of you recognize but all of you somehow knew. The Broken Oak looms ahead, its crown split by ancient lightning, and beneath it stands a figure in rain-sodden grey robes. It is only when they turn that you realize: it is both of you, yet neither. A ghostly echo of a woman, her eyes pooled with dark water, mouth opening to speak words that feel like drowning. "The oath calls," she rasps, and points downslope to where stone ruins crown a sinkhole, water pooling black and still as ink.
Description
The party arrives at the forest shrine where they receive their first clue. The Broken Oak is a landmark known to scholars of the area—a tree struck by a paladin's curse centuries ago. The apparition is a shade or false memory, potentially manifested by the patron's will or by something guarding the temple below. The ruins are the surface structure of the Temple of Tides, now half-submerged in a sinkhole that formed after an earthquake three winters past. The stone bears marks of old sacrificial altars—carved channels for blood, corroded bronze offering bowls.
DM Notes
This is the hook. The apparition cannot be attacked or harmed; it dissolves if touched or if any spell is cast at it. The monk may recognize her as resembling their sister or mother (DM's choice for added emotional weight). DC 12 Wisdom (Insight) reveals that all three adventurers are lying to themselves about why they came—there's compulsion here, possibly magical. The ghost fades after delivering her message, leaving only the scent of salt water and copper. The sinkhole descent is treacherous; DC 13 Dexterity (Acrobatics) to avoid slipping on moss-covered stone. Easier ropes are available if the party searches the nearby shrine (DC 10 Wisdom (Perception)).
Read Aloud
Cold water laps at your shins as you descend into the temple proper. The vaulted chamber before you is half-submerged, its high ceiling lost to shadow and moisture. Enormous stone pillars rise from the deep, carved with the writhing shapes of drowned figures and tentacles. Between them, you spot an altar on a dry platform—but something moves in the water. Shapes. Pale and wrong. A woman's laugh echoes from nowhere and everywhere at once, and in the murk below, you see eyes—too many eyes—opening in the dark.
Description
The Drowning Hall is the primary chamber of the Temple of Tides, a forgotten shrine to Umberlee (goddess of the sea, considered chaotic evil by most). The water is 15 feet deep at its center and frigid (Constitution saving throw DC 10 or take 1d4 cold damage each round of submersion beyond the first). The pillars are carved with blasphemies and Old Abyssal script invoking the deep ones and forgotten gods. The altar on the dry platform holds a ritual knife and a ledger bound in some creature's hide—the ledger contains names and dates, including the names of the warlock and cleric from eight years prior, with the entry "Pact Sealed in Salt and Sorrow." The shapes in the water are giant crabs (see Encounter 2). The laugh belongs to Merriessa, a drowned hag who once served the temple.
DM Notes
DC 14 Wisdom (Perception) to notice the altar before the crabs attack. DC 12 Intelligence (Religion) to recognize the Umberlee holy symbols and deduce this is a forgotten sea temple. The ledger is a powerful emotional prop: reveal that the warlock and cleric made a blood pact here eight years ago, witnessed by the cleric's sister (then only 13). The warlock's patron is connected to this temple—likely an old spirit or bound entity that the pact partially awakened. Merriessa is not hostile yet; she is testing them, curious if they've "returned to pay their debt." If the party speaks to the shadows before fighting, Merriessa offers a bargain: complete the ritual on the altar (requires fresh blood from each party member) and the temple will "rest" for another generation. Refusing the bargain triggers the encounter.
Monsters
Tactics
The three giant crabs emerge from the deeper water in staggered rounds (one each round, starting round 2). They are territorial and attack anything moving in their water. Crabs prioritize the closest target and use their grapple ability to drag victims into deeper water (Strength save DC 13 to resist). A crab that grapples will try to submerge its victim (requiring a DC 13 Strength or Dexterity save each round or begin drowning). If one crab is reduced below 7 HP, the others attempt to retreat to deeper water, but they will continue to attack if cornered or if victims enter the deep again.
Terrain
The Drowning Hall is half-submerged. Shallow water (3 feet) covers the outer edges; the center drops to 15 feet. The altar platform is dry and raised 6 feet above the shallow water—reachable by climbing or swimming. Giant pillars provide partial cover. The water is cold and visibility is limited (20 feet in the water due to murk). Any creature reduced to 0 HP in deep water begins drowning immediately.
Read Aloud
Gasping and dripping, you pull yourselves onto the altar platform. The ledger lies open before you, and your eyes land on names you did not expect to find together: yours, bound in faded ink and what you now realize is dried blood. Eight years ago. Your hands were here. Your blood sealed this. And beside the date is a name you do recognize—Theron Brightforge, a paladin of Helm, reported missing from a caravan near Baldur's Gate that same season. Merriessa coalesces from the water, no longer attacking but weeping—her form flickering like a candle in wind. "The debt remains," she says. "He was never delivered. The hunger grows. Choose: sacrifice one of yourselves to seal the oath anew, or flee—and let the entity beneath consume this land until the debt is paid in corpses."
Description
The altar chamber is now silent except for dripping water. The ledger is genuine and ancient, its pages recording centuries of sacrifices and pacts. The warlock and cleric will begin to remember fragments of their pact (DM reveals through evocative flashes, not exposition): the cleric's sibling was dying of plague; the warlock's patron promised a cure in exchange for delivering a holy warrior to the temple. The monk, seeing the ledger, realizes they were there—they remember being healed by miracle at the temple's deepest point. They also remember that Theron Brightforge was supposed to arrive, but never did. The warlock broke the oath eight years ago (either by choice or circumstance), and the consequence has been growing ever since.
DM Notes
This is a moral choice, not a combat encounter. The party must decide how to resolve the pact. Options: 1) Sacrifice one of their own (roleplay this consequence heavily). 2) Negotiate with Merriessa for a compromise (requires DC 14 Charisma (Persuasion); if successful, offer an alternative: hunt down what became of Theron and either bring proof of his death or bring him back). 3) Attempt to break the pact with magic or violence (Dispel Magic on the ledger, DC 15, or try to defeat Merriessa, which is difficult but possible—see her stats). 4) Attempt to contact the warlock's patron directly using a ritual (requires a warlock spell slot and DC 14 Arcana check; success grants an audience with a being of great power and malevolence). This scene should take 15-20 minutes of roleplay and decision-making.
Read Aloud
Whatever choice you make, the temple shudders. Cracks spider-web across the stone pillars. The water begins to rise—not gradually, but in a rushing tide that fills the chamber in seconds. Merriessa screams, a sound like a ship breaking, and her form dissolves into spray. The altar sinks. You have moments to reach the stairs, to climb out of the drowning hall before the entire structure collapses. As you scramble upward, gasping, you hear something vast move in the deep below—something that has been patient, something that has now decided to hunt.
Description
The temple is collapsing. This is a chase scene: the party must reach the surface before the temple floods completely. The water rises 10 feet per round. The stairs are 40 feet away and partially blocked by falling rubble. Any party member who falls into deep water must make a DC 13 Strength (Athletics) check to reach the platform. Those who fall to 0 HP while in water begin drowning immediately. Merriessa is gone, but the party hears a final whisper: "The debt is marked upon your soul. It will come due." As they reach the surface, they see something massive disturb the water below—a silhouette that is neither crab nor human, something that wears the shape of a face they almost recognize.
DM Notes
This is an action sequence designed to end the session on tension and mystery. If any party member is in critical condition, give them a moment to stabilize at the surface before moving to the conclusion. The collapse is not meant to kill anyone (unless players are extremely reckless); it is meant to drive urgency and create a sense of supernatural threat. The "something vast" is the warlock's patron—a thing that has been waiting centuries to be fed and is now actively hunting.
A leather-bound journal written in Old Abyssal and Chondathan. It records names, dates, and pacts made at the temple spanning 300 years. The warlock and cleric's names are written in blood on page 47. The ledger is magically preserved and waterproof. Scholars in Waterdeep would pay 50 GP for it, but its true value is in the secrets it contains—including the real name of the warlock's patron and hints of other adventurers who made similar pacts and vanished. (Treasure value: 25 GP equivalent in information; no direct sale value without risking attention from dark powers.)
A curved obsidian blade with a silver handle shaped like a drowned face. It was used for blood pacts and sacrificial rites. Non-magical but beautifully crafted. Worth 30 GP to a collector, but any cleric or warlock who touches it feels the cold weight of obligation. If used to deliberately wound a paladin or cleric, it grants advantage on the attack roll for that one strike, but the user must make a DC 13 Wisdom save or be compelled to complete the original pact. (Treasure value: 30 GP equivalent.)
A piece of strange coral that grows only in the temple's deepest chamber. It glows faintly blue in darkness and is warm to the touch. If kept by the cleric, it slowly heals 1 HP per day to anyone holding it, but requires the holder to make a DC 10 Wisdom save each dawn or suffer a nightmare of drowning. Scholars of the Moonstar Library in Baldur's Gate would pay 40 GP for it; Merriessa's spirit is partially tethered to this fragment and can communicate through it (once per three days, for 1 minute). (Treasure value: 40 GP equivalent.)
Story Hooks
These items directly seed the next session: The ledger reveals the real name and nature of the warlock's patron (a powerful entity called the Hunger or the Drowned King), which opens investigation and potential confrontation. The dagger's compulsion might force one of the party members to seek out Theron Brightforge or another paladin to 'complete' the pact, leading to a rescue or necromancy subplot. The coral fragment is a direct link to Merriessa and to the temple—it can be used as a focus for divination or communication with the entity below. Additionally, the fact that the party chose to flee (rather than sacrifice or negotiate) means the debt is now active and mobile—the entity will pursue them, possibly sending agents or manifesting in locations tied to the original pact-makers.
Conclusion
Wrap Up
The three of you collapse on the mossy earth at the Broken Oak, gasping and soaked, the temple now just a black hole in the forest floor. The summoning apparition is gone. Merriessa is gone. But you are bound to one another in a way you were not before—by shared knowledge of a sin you committed together, by the weight of a broken promise, and by the certainty that something in the deep is now hunting you with patient, ancient hunger. The ledger sits heavy in your possession. The ritual dagger catches moonlight. The coral glows softly, still warm from the depths. Waterdeep lies two days north. But are you safe anywhere, now that the pact is broken and the hunger is awake?
Cliffhanger
Three nights later, the cleric dreams of drowning. The monk wakes to find seawater on the inn room's floor—though you are nowhere near the coast. The warlock hears Merriessa's voice in the wind: "It knows your names now. It is coming." A ship bound for Waterdeep is found empty at the docks, the crew vanished. The captain's log reads: "The eyes have come. We are going down." Authorities in the city are baffled. But the party knows: the entity below has finally found a way to surface.
Next Session Hooks
- Investigate the disappearance of the ship's crew and discover it is connected to other vanishings in the past eight years—all people with names in the ledger.
- Merriessa's ghost continues to communicate through the coral fragment, warning of the entity's hunger and demanding the party find Theron Brightforge (alive or dead) to satisfy the pact before it is too late.
- The warlock's patron begins to speak more frequently, offering power in exchange for deeds that will either feed the entity or bind it further—forcing the warlock to choose between service to the patron or loyalty to their companions.
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