A character who draws the Throne card from a Deck of Many Things gains ownership of a keep. But how big is the keep, and what are its defenses and layout? What lives in the keep now, and what must the characters do to secure it? This chapter, intended for DMs, presents Harrowhall, a castle plagued by an evil necromancer, as an example of such a keep. The Throne card doesn't need to appear in your game for Harrowhall to be useful; exploring the haunted castle makes an excellent single-session adventure, especially for characters in need of a place to recuperate between adventures.
Introducing Harrowhall
A character who draws the Throne card from a Deck of Many Things has a fleeting vision of a keep surrounded by a dry moat. Fog swirls across the grounds, and the castle appears abandoned by its owners. Instead of courtiers and guards, spectral figures appear behind narrow windows, and a huge serpentine creature slithers through its courtyard. Nevertheless, the stone walls are tall and undamaged, and an astronomical observatory boasting several telescopes surmounts the second floor of the inner structure. Harrowhall would make a fine stronghold for a group of adventurers, but it won't be easy to claim.
Place Harrowhall in a location appealing to the characters but also useful to your ongoing campaign. For example, the keep might be near a big city the characters like to visit, but also close to a crossroads that ensures travelers could appear at the castle's gate at any time. The keep might have always been in this location, avoided by locals thanks to the spirits that lurk there, or it might have been summoned by the magic of a Deck of Many Things. Regardless, the character who draws the Throne card knows where the keep is located and feels it tugging on their consciousness when their mind is quiet.
If you aren't using the Deck of Many Things, the characters can discover Harrowhall another way. Introduce the keep when your players are ready for their characters to have a stronghold they can call their own. The castle's fearsome reputation provides plenty of incentive for altruistic heroes to explore the site and put an end to the schemes of a ghostly necromancer, but if the characters have been talking about building a headquarters, they can drive off the ghosts that haunt Harrowhall and claim it for their own.
Harrowhall's Story
Years ago, a wizard named Gremorly drew the Throne card from a Deck of Many Things, gaining ownership of a small castle called Sovereign's Keep. Gremorly was a necromancer and misanthrope who had little patience for the living; he resolved to use the keep to create and house a ghostly army he would use to seize power. Gremorly performed a ritual that turned Sovereign Keep into a ghost trap: anyone who dies within the castle walls rises as an incorporeal spirit, trapped within the castle. Then, he waited. When adventurers came to investigate the seemingly abandoned keep, Gremorly murdered them and trapped their ghosts. But fortune recently turned against Gremorly when a behir entered the keep seeking a nest. It slew Gremorly, who became a victim of his own ritual.
Gremorly is now one of the many ghosts that haunt the keep. Locals have renamed the keep Harrowhall, as they dread the spectral figures moving through the fog there and the fierce lightning storms that erupt without warning. (The behir is the source of this lightning, but the locals don't know that.)
Adjusting for Party Level
Harrowhall is designed to be a challenge for four 8th-level characters who explore the keep in a single session. Decrease the challenge for characters lower than 8th level. Conversely, increase the challenge for groups with more than four characters, with characters higher than 8th level, or that revisit the keep over multiple sessions.
Decreasing the Challenge
If Harrowhall is too challenging for your group, but you want the characters to have a keep, you can use these strategies to decrease the difficulty:
Increasing the Challenge
If Harrowhall isn't sufficiently challenging for your group, here are ways to make it more difficult:
Exploring Harrowhall
Keep the following information in mind while the characters explore the haunted keep.
Ghost Trap
Gremorly's ritual forces any Humanoid who dies within the keep to return as a ghost that's unable to pass beyond the keep's walls. The ritual can be broken by disassembling, moving, or destroying all three ritual rods, which the necromancer placed in the armory (14), the kitchen (14), and the observatory (14). Each rod is protected by a Glyph of Warding. Once the ghost trap is broken, all the ghosts in the keep can leave except Gremorly, who remains to haunt the observatory.
Side Effects
When the characters first arrive at Harrowhall, a thick and unsettling fog covers the grounds and many of the castle's rooms. The fog is a side effect of the ritual. As long as Gremorly's ritual remains in effect, the keep remains cold, foggy, and inhospitable.
Trapped Ghosts
Three groups of adventurers who dared to explore Harrowhall were killed by Gremorly and are now trapped in the keep. Fate's Devout are in the dining hall (14), the Spellseekers are in the eastern bedrooms (14), and the Gloved Hand are in the crypt (14). Each group can be customized to fit your campaign; for example, Fate's Devout might serve a prominent deity of fate in your setting, the Spellseekers might be Red Wizards of Thay, and the Gloved Hand might be Harpers.
The ghosts all hide from Gremorly. Although they know of the necromancer and the presence of other ghosts, they have forgotten most of what they knew in life, recalling little beyond the mission that brought them to the keep. The ghosts aren't hostile and act as allies to characters willing to help them. Destroying the ghosts is difficult, as they remain on the Border Ethereal and can't affect—or be affected by—anything on the Material Plane. The ghosts defend themselves if the characters attack them.
Behir
A behir has made its nest in the keep's watchtower (14), but the monster hunts throughout the keep. Characters might spot it at any time, and it might test their strength in a brief encounter before retreating to attack again later. If the characters take their time and the adventure needs more excitement, the behir could attack and fight to the death.
The behir knows the corridors of the keep so well that it can move through a 10-foot-wide space, as well as any door in the keep, without squeezing.
Harrowhall Features
Unless otherwise stated, Harrowhall has the following features:
Harrowhall Locations
Harrowhall has held up well in the centuries since its creation, apart from a few missing stones and shattered windows due to recent neglect.
The following areas in Harrowhall are keyed to map 15.1.
1: Moat and Walls
A 30-foot-high wall borders Harrowhall, surrounded by a 20-foot-wide, 15-foot-deep, dry moat. The drawbridge is down, and the portcullis is up. Read or paraphrase the following if the characters get close enough to see into the moat:
Gremorly dumped the corpses of those he killed into the moat. A character who examines these remains and succeeds on a DC 15 Wisdom (Perception) check notices some skeletons have matching emblems on their clothing or gear, perhaps indicating the bearers belonged to the same organization. If you have decided the dead adventurers belonged to well-known organizations like the Harpers or Red Wizards of Thay, the symbols of those groups can be found among the corpses.
Treasure
Gremorly left treasure on the bodies of his victims to lure more people into the castle. Searching the corpses uncovers 750 gp, 50 pp, and a jeweled ring worth 250 gp.
Crossing the Moat
The characters can use the drawbridge to cross the moat. They can instead clamber through the moat with more time and effort. No check is required, but it's a grisly detour, and the moat is 8.
Portcullis
The portcullis is up, and nothing prevents entry to the keep. The mechanism to lower the portcullis is in area 2. Were the portcullis to be dropped, lifting it manually would require a successful DC 22 Strength (Athletics) check.
Scaling the Walls
The castle's walls are high and difficult to climb. Creatures trying to climb the walls must succeed on a DC 15 Strength (Athletics) check or fall.
2: Watchtower
Any furniture that once stood in this room has been ground to splinters by the behir that has claimed this tower as its nest. The behir isn't here when the characters enter the keep; it prowls the keep, looking for a fresh meal.
Stairs ascend 30 feet to a second floor that is even with the keep's battlements. This upper room is filled with levers and pulleys that control the drawbridge and portcullis mechanisms. A creature can use an action to raise or lower the drawbridge or the portcullis in area 1.
3: Armory
This room is filled with shortswords, crossbows, shields, and maces placed here by the folk who owned the keep before Gremorly.
Ritual Rod
Set into a metal tripod in the center of the room is a 3-foot-long metal rod decorated with runes and glowing with necromantic magic. The entire assembly weighs 8 pounds. This is one of three rods Gremorly set up to turn Harrowhall into a ghost trap. If the rod is removed from its tripod or destroyed, the necromantic energy fades and the rod becomes nonmagical. The rod and tripod assembly has AC 19, 5 hit points, and immunity to poison and psychic damage.
The rod is protected with a Glyph of Warding; if anyone comes within 5 feet of the rod or anything touches it, explosive runes on the rod fill the room with acid. All creatures in the room must make a DC 15 Dexterity saving throw, taking 5d8 acid damage on a failed save, or half as much damage on a successful one. Once the glyph has gone off, or if it is dispelled, the ritual rod can be safely moved, destroyed, or disassembled. The glyph doesn't activate if the rod is moved without anyone touching it or approaching it, such as by using the Mage Hand cantrip. Knocking the rod over by throwing an object at it triggers the explosive runes.
4: Courtyard
This open-air courtyard connects the keep's entrance to various other buildings on the grounds.
Stables
These stables contain saddles and other equipment hanging on the walls, but no animals; the behir ate Gremorly's horse.
Statue
A Large statue of Istus, a god of fate and the creator of the first Deck of Many Things, stands in the center of the courtyard. She's depicted as a solemn-faced woman holding a spread of cards. The statue is a stone golem intended to protect the keep for its rightful owners—who might be the characters, thanks to the magic of the Deck of Many Things. But Gremorly's ghostly presence has confused the golem, and it doesn't recognize the characters as the keep's new owners. If the characters approach the golem, it frees itself from its plinth with a deep cracking sound and attacks until destroyed. However, if the characters destroy Gremorly's ghost and this golem is still intact, it becomes their ally and defends this courtyard on their behalf.
5: Crypt Entrance
This room is mostly empty. One outer wall has a stained-glass window. Stairs lead to the crypt below. If the characters haven't encountered the Gloved Hand (14) yet, they hear the faint echo of an argument coming from below.
6: Dining Hall
Read or paraphrase the following when the characters reach this room:
In life, the three ghosts were an adventuring party known as Fate's Devout. Wielding divine magic, they traveled across the realm to carry out Istus's will. They came to this keep because they heard it was holy to Istus, but Gremorly killed them.
The ghosts are alarmed by the unholy magic gathering in the keep's chapel (14), a side effect of Gremorly's ghost trap ritual being unsupervised for so long. They want to purify the chapel and escape the keep, but they're afraid of Gremorly. When the characters arrive, the ghosts are debating their next course of action, which is made difficult by the fact that the ghosts remember only the most recent events clearly.
The leader of Fate's Devout is Moira Stonehearth, who was a priest in life. The other members are Gunter Granitefist and Ragar Onyx. When the three notice the characters, Moira asks for aid. She tries to be warm and friendly, but her imprisonment in Harrowhall has damaged her memory. She explains that none of the ghosts can escape the keep or pass on due to a ritual performed by a powerful necromancer who lives here. Moira doesn't know Gremorly's name or that he is dead. She knows the keep holds other ghosts but knows nothing else about them.
Moira asks the characters to go 120with her and her companions to the chapel and defend them from the evil magic there while they attempt to reconsecrate it. She hopes reconsecrating the chapel to Istus will break the ritual and allow the ghosts to move on, but it won't. Moira can teach the consecration ritual to anyone who speaks Dwarvish, but she offers only if asked. Teaching the ritual takes an hour. See area 11 for more on performing the consecration ritual.
These dwarves know the location of the chapel (14) and can lead the characters there if the characters agree to help. Otherwise, the ghosts won't leave the dining hall.
7: Kitchen and Pantry
This room has several ovens and cupboards full of old pots, pans, and utensils. A pantry at one end holds rotted supplies.
Ritual Rod
A second ritual rod, identical to the one in the armory (14), stands in the center of the kitchen. This rod is also protected by a Glyph of Warding, but if triggered, the explosive runes deal cold damage instead of acid damage.
Treasure
A character who succeeds on a DC 15 Wisdom (Perception) check or spends half an hour searching the pantry finds an Alchemy Jug among a few bags of spoiled flour on the floor.
8: Western Bedrooms
These bedrooms are mostly empty, save for bedside tables and musty beds. The sole inhabitant of these rooms is Gus, Gremorly's old black cat, who was killed by the behir and now is a Tiny ghost. Gus is friendly to anyone who offers him food, even if he can't eat it, and he follows the characters as they explore the keep, meowing whenever doing so won't alert an enemy. (Gus might be old, but he still knows how to hunt.)
Treasure
Gremorly slept in the southernmost bedroom. A diary on the bedside table details his life and wicked agenda. Several references to a book titled Exploring Arcanum make it clear the ghost trap ritual can be found in that book. In one passage, Gremorly gloats over attuning himself to a Staff of Withering.
A food bowl on the floor is inscribed with Gus's name. In addition, a Potion of Growth has rolled under the bed.
9: Throne Room and Study
Huge stained-glass windows grace the walls of this room. Its vaulted ceiling is 20 feet tall. Thrones, each inscribed with a character's name, sit at the far end of the room in a semicircle. A small room to the west is for private meetings and is furnished with a couch, chairs, and cabinets.
Two helmed horrors—one in the southeast corner and one in the southwest—stand guard in the throne room. While motionless, they look like ordinary suits of armor, but when the characters enter the room, the horrors animate and attack. Like the golem in the courtyard, these constructs guard the keep on behalf of its rightful owners but the presence of Gremorly's spirit confuses them. If the characters defeat Gremorly and these helmed horrors have not yet been destroyed, they become allies to the characters and defend this room on their behalf.
Treasure
If a character drew the Throne card from a Deck of Many Things, a golden circlet rests on that character's throne. This circlet has the powers of a Helm of Telepathy. One of the cabinets in the study includes twelve bottles of rare wine, each worth 25 gp.
10: Eastern Bedrooms
Read or paraphrase the following when a character opens the door to one of the bedrooms:
In life, the six ghosts were a group of traveling scholars called the Spellseekers. Two of the Spellseekers were human, one was a dwarf, one was an elf, and two were dragonborn. Their leader, a dragonborn ghost named Patrin Umbyrphrax, calmly asks the characters what brings them to the keep. Patrin explains that he and his colleagues sought a book called Exploring Arcanum, known to be in the possession of a necromancer named Gremorly. Rather than granting their request and letting them read the book, Gremorly killed them and trapped them as ghosts with a ritual. Patrin remembers little—his memory is fading due to his Undead status—but he is certain the details of the ghost trap ritual could be found in Exploring Arcanum, which he last saw in the keep's library. The Spellseekers don't know any other details of the ghost trap ritual, nor do they know that Gremorly is dead.
Patrin knows where the library is and offers to guide the characters to it. He warns them it's home to a nest of phase spiders, which travel the Ethereal Plane and can destroy ghosts. Patrin tells the characters that if they defeat the phase spiders, they can get the book and use it to break Gremorly's ritual, releasing the ghosts trapped in Harrowhall.
11: Chapel
This chapel is dedicated to Istus, the god of fate who created the first Deck of Many Things. Gremorly's ghost trap ritual has persisted so long without his supervision that necromantic energies have begun to gather in the chapel, corrupting it.
A statue of Istus, surrounded by a web of multicolored threads, stands behind an altar in the southern part of the room. The altar emits a pulsating dark haze; anyone who touches the altar takes 17 (5d6) necrotic damage and must succeed on a DC 15 Constitution saving throw or gain 1 level of exhaustion. Shadows fill the corners of the room; a light source that usually provides 2 provides only 2 within the chapel, and a light source that normally provides 2 is useless.
Reconsecrating the Altar
The corruption of this chapel persists even if Gremorly's ritual is broken. But the members of Fate's Devout—the ghostly adventurers in the dining hall (14)—know a ritual to purify the place. They tried it once but were attacked by "unholy beings" and fled. If the characters bring Fate's Devout back to the chapel, they'll try this ritual again, asking the characters to protect them from harm.
The three ghosts gather around the altar, chanting an ancient prayer in Dwarvish. They must stay on the Material Plane for the duration of the ritual. Shortly after the ghosts begin praying, three shadow demons seep from the corners of the room. The demons attack the ghosts, but a demon that's attacked by a character shifts its focus to that character. When two shadow demons are killed, the remaining one flees. After 3 rounds, if all the ritual's participants are still chanting, the ritual succeeds, and the necromancy suffusing the chapel vanishes. If a ghost is reduced to 0 hit points, a character trained in the ritual can replace the fallen ghost, but the character must stand adjacent to the altar and use their action each round for the remainder of the ritual to chant the necessary incantations. If the ritual fails, surviving members of Fate's Devout can try again, but they might need further help from the characters, as three participants are required.
12: Balcony
This balcony overlooks the keep's rear courtyard. If the characters have not yet encountered the behir, it is lurking between the kitchen and throne room when they emerge. Characters must succeed on a DC 17 Wisdom (Perception) check to avoid being 3 by the behir when it attacks. The behir fights to the death, defending its hunting grounds.
13: Library
Three phase spiders lair in this room and attack any creature that enters.
This spiderweb-covered library contains hundreds of books in genres ranging from history and religion to speculative fiction. Gremorly added his impressive personal collection to the library, including many rare tomes on necromancy, but most of the books were here when he arrived. The patches of webbing on the floor are 8. These webs burn up instantly when touched by flame, but flames could also set the library on fire.
Exploring Arcanum
Once the characters deal with the phase spiders, they—or the Spellseekers from 14—can search for Exploring Arcanum, a book from Gremorly's collection that includes the ritual he used to make his ghost trap. Characters can find the tome with 10 minutes of careful searching. The book explains how the ritual rods must be placed and how to safely move them; any character who reads this ritual can move or dismantle the ritual rods without triggering their Glyphs of Warding.
14: Crypt
Three ghosts bicker in this small crypt. Read or paraphrase the following when the characters enter the crypt:
These are the ghosts of the Gloved Hand, professional thieves who tried to rob Gremorly's keep. The necromancer killed them, and they've been arguing over who is to blame ever since. They're not sure how long it has been, as they can barely remember anything before they arrived at the keep. Their only solace has been watching the behir kill Gremorly. They know his ghost is trapped here, too.
The ghosts initially ignore the characters, but they notice if the characters take dramatic action to gain their attention. Kilea Ondren, the ghost of the tiefling woman who led the Gloved Hand, explains the group's predicament. (Her subordinates blame each other for their deaths, and they interrupt constantly.) The members of the Gloved Hand know nothing about the ghost trap ritual and have no advice about how they might be freed. The ghosts know that Gremorly mostly kept to the observatory before he was eaten by the behir, and that's where his ghost can probably be found.
15: Observatory
This room has a domed glass ceiling and contains three large standing telescopes, each covered in dust. A large, round table in the middle of the room bears old, faded maps that depict the Sky of Many Things (see 12). A staff leans against the table, and a book lies atop it (see the "Treasure" section below).
Ritual Rod
A third ritual rod, identical to the one in the armory (see 14), stands in the northwest corner of the room. This rod is also protected by a Glyph of Warding, but if triggered, the explosive runes deal fire damage instead of acid damage.
Gremorly's ghost (see the accompanying stat block) haunts the observatory. He appears as a translucent human figure wearing trousers, shoes, a long coat with wide sleeves, and a wizard's hat. He has a long beard and bushy eyebrows, and he carries a ghostly staff. Gremorly has forgotten the circumstances of his death and goes about his business as if he were still alive. He moves from one telescope to another, occasionally consulting the astronomical charts on the table or checking the ritual rod. He doesn't notice the characters unless they interact with him or the ritual rod. If the characters draw his attention, he snickers with glee. "More fodder for my ghost army," he says, raising his staff. "I hope you've made peace with your gods." Gremorly fights until he is destroyed.
Treasure
The staff Gremorly holds is a spectral reflection of his real Staff of Withering, which leans against the table. Gremorly's spellbook lies on the table with the maps. It contains numerous spells, about half of which are necromancy spells, including all the spells in his stat block.
Escaping the Ghost Trap
When all three ritual rods are dismantled or destroyed, the ritual that traps the ghosts in Harrowhall ends. The thick fog that surrounds the keep lifts, and the ghosts can depart. A few might offer to remain, depending on their interactions with the characters:
Ghost cats are just as sweet, mischievous, and playful as their living counterparts. Euryale and I almost adopted one, but he kept trying to hunt Euryale's hair.