Tome of Horrors 2020 Cards Deck THREE
5e Binguai: ? Bloody Bones: ? Bog Corpse: If a creature in a coma caused by a bog corpse is placed in the sacred bog the corpse guarded, that creature becomes a bog corpse in 1d6 days. Bone Reaper: ? Cat Undead Feral: ? Corpsespun: ? Crawling Hand: ? Draug: ? Draug Captain: ? Duppy: ? Egui: ? Egui, Ghost: ? Ekimmu: ? Fear Guard: Any living creature reduced to Wisdom 0 by a fear guard is slain and becomes a fear guard under the control of its killer in 1d6 rounds. Gholle: ? Ghoul: Any humanoid creature slain by the gholle rises as a ghoul within 1d6 hours. Ghoul of Khemit: ? Ghul: ? Ghul, Undead Djinn: ? Groaning Spirit: ? Guardian Shade: ? Hoar Spirit: ? Hyaenodon Undead: ? Lacedon: ? Mian'shen, Masked Spirit: ? Don'gui, Ice Wraith: ? Murder Born: ? Murder Crow: ? Red Jester: ? Greater Shadow: ? Swarm of Undead Bats: ? Swarm of Undead Hummingbirds: ? Swarm of Undead Rats: ? Shadow Wolf: ? Aqueous Zombie: ? Bramble Zombie: ? Carcharodon Zombie: ? Goblin Zombie: ? Gug Zombie: ? Juju Zombie: ? Mummy Zombie: ? Otyugh Zombie: ? Poisonous Snake Zombie: ? Sphinx Zombie: ? Undead: ? Shadow: If a non-evil humanoid dies from [a greater shadow's strength drain] attack, a shadow rises from the corpse 1d4 rounds later under the greater shadow’s command.
If a non-evil humanoid dies from [a shadow wolf's strength drain] attack, a new shadow rises from the corpse 1d4 hours later. Skeletal Statue: Bone Cobbler's Animate Bones power. Skeleton: ? Zombie: A humanoid slain by [a duppy's incorporeal touch] attack rises 24 hours later as a zombie under the duppy’s control, unless the humanoid is restored to life or its body is destroyed.
A victim slain in this manner [by a cerebral stalker's consume brain attack] reanimates in 1d4 rounds as a zombie. Zombie, Newly Undead Friend: A victim slain in this manner [by a cerebral stalker's consume brain attack] reanimates in 1d4 rounds as a zombie. Typically, the cerebral stalker “tosses” them back up to the surface of the ground so their traveling companions can witness the reanimation and deal with their newly undead friend.
Animate Bones (1/day). A bone cobbler animates up to five skeletal statues within 30 feet of itself. These creatures use the stat block of skeletons, though their forms and structures do not need to resemble humanoids or anything remotely humanoid. The skeletal statues remain animated until destroyed, until the bone cobbler wills them back into statues, or for 24 hours.
Tome of Horrors 2020 Instant Encounters Volume One (5e)
5e Sword Wight: ? Sword Wight, Wicked Depraved Creature, Undead Abomination, Warped Twisted Caricature: ? Standard Wight: ? Zombie: A humanoid slain by [a sword wight's life drain] attack rises 24 hours later as a zombie under the wight’s control, unless the humanoid is restored to life or its body is destroyed. Sword Wight, The Thing in the Barrow, The Monster Beneath the Hill, Horrible Creature: ?
Tome of Horrors 2020 Instant Encounters Volume Three (5e)
5e Brine Zombie: Brine zombies are the remnants of a ship’s crew that has perished at sea.
The spark of evil that brought them back from the ocean depths drives them to seek the living so they may join them in their watery graves.
A few years ago Silas Hawthgrow and his crew of smugglers off loaded a small fortune in illicit goods from the pirate ship Lost Fools. It was a dark moonless night and the crew struggled against an ebbing tide to bring their skiff in to their landing point in a hidden cove. They failed and ended up on the rocks. While awaiting the return of the tide, a sudden squall caught the skiff and drove it into a small sea cave. Silas and his crew died, but their sudden death committing in the course of committing a crime turned their corpses in to brine zombies. Brine Zombie, Rotting Humanoid, Remnants of a Ship's Crew That Has Perished at Sea, Mindless Creature: ? Silas Hawthgrow, Brine Zombie: A few years ago Silas Hawthgrow and his crew of smugglers off loaded a small fortune in illicit goods from the pirate ship Lost Fools. It was a dark moonless night and the crew struggled against an ebbing tide to bring their skiff in to their landing point in a hidden cove. They failed and ended up on the rocks. While awaiting the return of the tide, a sudden squall caught the skiff and drove it into a small sea cave. Silas and his crew died, but their sudden death committing in the course of committing a crime turned their corpses in to brine zombies. Brine Zombie, Shambling Bloated Shape: ?
Tome of Horrors 2020 Instant Encounters Volume Four (5e)
5e Pyre Zombie: Pyre zombies are the sad, tortured remains of those who were killed just before being burned alive. When the soul departed, their bodies were taken over by some malignant spirit. The spirit fortified the bodies from destruction by the fire, and the undead forms escaped the pyre to wreak vengeance on the living. Pyre Zombie, Ashen Form, Thing, Singed Corpse: ? Pyre Zombie, Rotting Corpse, Sad Tortured Remains of One Who Was Killed Just Before Being Burned Alive, Undead Form: ? Animated Creature: The electrical aura of the fogwarden can animate up to four dead creatures within 20 feet. Zombie: ? Skeletal Knight: Once bound to their master as a personal guard, a skeletal knight returns when called to defend its lord once again. Skeletal Knight, Guardian: Millennia ago, the Hyperborean nobleman Allisus Athrusa ordered that a great tomb be crafted. He placed a portion of his vast fortune as well as six guardians into this tomb. These bodyguards, slaves in his service in life, were slain and their remains animated as skeletal knights. If this great tomb were ever to be destroyed, the guardians would awaken to slay all trespassers.
Tome of Horrors 2020 Instant Encounters Volume Five (5e)
5e Crypt Thing: Crypt things are undead creatures found guarding tombs, graves, crypts, and other such structures. They are created by spellcasters to guard such areas and they never leave their assigned area. Crypt Thing, Skeletal Humanoid: ?
Tome of Many Things (5e)
5e Undead, Undead Creature, Undead Being: Creatures killed by a heavy water grenade rise as undead beings 1 hour after death unless steps are taken to prevent this. Spirit of Death, Spirit of the Underworld: ? Vile Undead Creature: ? Grim Morigan the Fallen, Undead Human Paladin 5: Very little is known about the individual known as Grim Morigan the Fallen. It is believed they were once a Paladin who took an Oath of Vengeance, however, sometime later they broke that oath after a time of exile. An excerpt from a forgotten journal rumored to have been written by Morigan during his exile does shed some light on his motives: "I found death when I showed weakness in exile and indulged in self-pity instead of keeping my oaths ...
... my mind was restless. I returned from the black plain of Thanatos, the Abyss, the belly of death … sworn to a new oath to Orcus himself ... bringing all those to his kingdom who would get in my way from now on ...
... for centuries, I am chained to this oath. The demon prince will never acknowledge the debt as being paid off: I know that now...
... so ... Orcus must fall! Will fall! ... my patience will pay off in the end, instead. Only the right opportunity is missing... only so long! But sooner or later, this moment will present itself. When revealed: I will become the scythe of death, myself. I will become the grim reaper! This shall be my final oath ... " Lich: After that horrific act, she fell deeper into depravity as she began to experiment on living creatures to find the secret to immortality. Decades, and hundreds of dead test subjects later, she succeeded in becoming a Lich. Vampire: ?
Tomes of Dark Secrets (5E)
5e Fossil Skeleton: A fossil skeleton is animated from the petrified remnant of a primitive and primordial creature, its ossific remains calcified into eternal stone.
These undead could be used as undead encounters by the GM, or at the GM’s option a spellcaster could use animate dead to bring one of these creatures to unlife rather than a typical skeleton or zombie. Such undead otherwise follow the normal rules for animate dead. Mummified Zombie: A mummified zombie is a creature whose desiccated corpse has been both naturally and magically preserved and given unholy life. Possessed of great strength and durability, the bodies of mummified zombies are dry and dusty beneath their funerary wrappings (for zombies created in blasphemous rites for the dead) or the shrunken, leathery skin that clings to their bodies for those whose bodies were naturally preserved in sand, mud, or otherwise.
These undead could be used as undead encounters by the GM, or at the GM’s option a spellcaster could use animate dead to bring one of these creatures to unlife rather than a typical skeleton or zombie. Such undead otherwise follow the normal rules for animate dead. Fossil Skeleton, Ancient Animated Dead, Variant Undead Creature: ? Mummified Zombie, Ancient Animated Dead, Variant Undead Creature: ? Undead, Undead Creature: ? Fleshy Undead: ? Skeletal Undead: ? Incorporeal Undead: ? Sentient Undead Creature: ? Undead That Is Immune to the Charmed Condition: ? Undead That Was Not Humanoid in Life: ? Undead That Was Considered Humanoid in Life: ? Ghast: In addition, a spellcaster of any class wearing the Spellbones of the Devourer can prepare and cast create undead using a 5th-level spell slot; however, she can create only ghouls or ghasts with this spell. Ghoul: In addition, a spellcaster of any class wearing the Spellbones of the Devourer can prepare and cast create undead using a 5th-level spell slot; however, she can create only ghouls or ghasts with this spell. Ghoul, Fleshy Undead: ? Typical Skeleton, Skeleton of Brittle Bone, Ordinary Skeleton: ? Vampire: ? Vampire, Fleshy Undead: ? Wight, Fleshy Undead: ? Zombie, Common Zombie, Typical Zombie: Necrophagic Spell feat. Zombie, Fleshy Undead: ?
Your spells infuse the dead with a ghastly hunger for flesh.
Prerequisite: Able to cast animate dead or create undead
Benefit: When you cast a spell that deals damage, you take necrotic damage equal to the level of the spell. This infuses the spell with necromantic power, causing any humanoid killed by the spell to be temporarily reanimated as a common zombie. The zombies reanimate 1d4 rounds after death, and they remain animated for a number of rounds equal to the level of the spell that slew them. These zombies are uncontrolled and attack the nearest creature, living or undead, though they ignore the caster and non-living creatures or creatures that lack a body made of flesh and/or bone, such as plants and oozes. If targets are equidistant, determine randomly which it chooses.
Tooth and Nail: Creatures of Hereva (5e)
5e Oversized-Posh-Zombie-Canary: They say all legends have a small and humble origin. But the Oversized-Posh-Zombie-Canary, had the most extravagant, colorful, flashy, grandiose and massive of the humble beginnings that have ever been.
As a result of the experimental magic of the witches, the creation of the Oversized-Posh-Zombie-Canary was witnessed by hundreds of people, thousands of citizens suffered its fury and the whole world now fears its return. Undead: ?
Town Backdrop: Dulwich (5e)
5e Skeleton: Driven insane while adventuring in Gloamhold, Orkus worships Braal by animating the dead of Dulwich.
Thoroughly insane, Orkus enjoys animating the corpses in the Dulwich Cemetery and letting them run amok. Ice-Wreathed Skeleton: ?
Trail of the Apprentice: The King's Curse (5E)
5e Undead Soldier: Leading the commoners who would help her fight, she stood against an army of undead soldiers, raised by a necromancer who attacked when her father’s army was no longer able to defend his lands. Undead, Living Dead: ? Walking Dead: ? Flesh-Eating Ghoul: ? Zombie: ? Ghost: ? Vampire: ? Ghoul: ? Ghoul, Man-Like Figure: What none knew at the time of the collapse was that two men, servants from Wolfe Manor, had robbed the Lord Mayor and were escaping through the tunnel. The falling debris killed them and their bodies were never discovered.
Being so close to the museum, the vengeful powers of Akhutan have touched their unhallowed grave, transforming them into ghouls. Skeleton: ? Mummy, Risen Mummy, Powerful Undead, Typical Mummy: ? Sehetep, Skeletal Champion, Servant of Udimu: The thieves disturbed the King’s rest when they took a gem from his sarcophagus, and vengeful spirits of Akhutan responded with terrible magic.
When the foolish thieves removed the large ruby from Udimu’s sarcophagus, his bodyguard, Sehetep, immediately rose as a skeletal champion, bursting from his own sarcophagus to defend his master.
The power of Udimu’s curse first raised his bodyguard, Sehetep, from the dead. Mereret, Skeleton, Servant of Udimu: The thieves disturbed the King’s rest when they took a gem from his sarcophagus, and vengeful spirits of Akhutan responded with terrible magic.
King Udimu’s queen, Mereret, and three servants reanimated shortly after Sehetep.
The power of Udimu’s curse first raised his bodyguard, Sehetep, from the dead. Udimu’s queen, Mereret, and three of their servants soon followed. Skeleton, Skeleton Servant, Servant of Udimu: The thieves disturbed the King’s rest when they took a gem from his sarcophagus, and vengeful spirits of Akhutan responded with terrible magic.
King Udimu’s queen, Mereret, and three servants reanimated shortly after Sehetep.
The power of Udimu’s curse first raised his bodyguard, Sehetep, from the dead. Udimu’s queen, Mereret, and three of their servants soon followed. King Udimu, Mummy, Long-Dead Leader, Angry King: The thieves disturbed the King’s rest when they took a gem from his sarcophagus, and vengeful spirits of Akhutan responded with terrible magic. Mummy Lord: ?
Trail of the Apprentice: The Oracle's Test (5E)
5e Undead, The Dead, Undead Creature: ? Zombie: The fates of those who venture into Ithmar are not always known. Some who fall without receiving proper burial may be animated by tendrils of evil energy that worm through the earth. Zombie, Humanoid Shape: ? Skeleton: ? Will-o-Wisp, Small Glowing Orb, Aberrant Creature That Feeds on Fear: ?
Trail of the Apprentice: The Thieves' Den (5E)
5e Zombie: A coven of hags can change the weather, create zombies, gain visions of the past, present, or future, glean knowledge from beings outside of the Material Plane, and work other dark magic to terrorize the lands around their lair.
Create Specter. The wraith targets a humanoid within 10 feet of it that has been dead for no longer than 1 minute and died violently. The target’s spirit rises as a specter in the space of its corpse or in the nearest unoccupied space. The specter is under the wraith’s control. The wraith can have no more than seven specters under its control at one time.
Traveler's Guide to Angoria
5e Wyrd: Wyrds are witches and other magic users whose spirits have returned to their decaying body with the power of their two orbs, one dark amber in color, the other sickly green.
The first Wyrds were rumored to be elves, but eventually the curse spread to other magic users of other races, and wyrds have become one of the most dreaded undead creatures in the Known World. Dune Ghoul: "Sometimes, those who die in the sand, don't stay..." -Late Emir Tanapur
They can often be found near ancient ruins, and legends say the dune ghouls are the ancient warriors of a long lost civilization that fell to the temptation of Entropy. Nachzehrer: Nachzehrers are a magic experiments, an unholy cross of trolls, vampires and ghouls. They broke out of containment, and now spread their affliction to new corpses and seek flesh to gorge on. Wendigo: Hunger, despair, and death. These are the things that make a Wendigo.
Wendigos were once a Moorvalish experiment, where peasantry was forced into cannibalism until they were twisted into undead horrors, but they fled their captivity and now stalk the forests and mountains of the Known World.
If the Wendigo is slain, it will transfer its curse to a creature of its choice. That creature becomes a Wendigo upon death. Remove Curse can banish the Wendigo from its host. Slaughterspawn: Raised from the bleak Slaughtermarshes of Moorvale, the Salughterspawn wander endlessly in their grim marshy nests, where the wizards and monster hunters employed by the imperial throne slay them for a living. Slaughterspawn Wretch, Twisted Undead: ? Slaughterspawn Boomer: ? Slaughterspawn Arachnid: ? Slaughterspawn Phalanx: ? Slaughterspawn Undying, Fallen Knight: ? Wyrd, Dreaded Undead Creature: ? Dune Ghoul, Worst Nightmare of Any Desert Warnderer: ? Nachzehrer, Magic Experiment, Unholy Cross of Trolls Vampires and Ghouls, Corpse, Savage Horror of the Dark Nights, Beast: ? Wendigo, Undead Freak of Nature, Undead Horror: ? Wendigo, Freak: ? Slaughterspawn Wretch, Twisted Undead: ? Slaughterspawn Boomer, Bloated Corpse: ? Slaughterspawn Phalanx, Writhing Mass of Dead: ? Undead, Undead Monster: The Desert of Solitude is an endless, bleak expanse of dunes as far as the eye can see. Nothing can live here, except the undead left behind from Unlight's corruption. Freak: ? Undead Monster: ? Undead Scourge: ? Wandering Undead: ? Death Knight: ? Sir Karathus, Death Knight: ? Ghost: ? Ancestral Ghost: ? Ghoul: ? King Maedion the Risen, Lich: ? Revenant: ? Undead Skeleton, Skeletal Form: Potion of Skeletal Projection magic item. Skeleton: ? Vampire: ? Wight: ? Karr-Daron, The Silent Warlord, Wight: ? Wraith: ?
Potion of Skeletal Projection
When you drink this chalky potion, your skeleton emerges from your body and is animated as an undead skeleton, which you inhabit and control. Any damage or other effects that apply to your skeletal form have no effect on your flesh body, nor do they persist when you return to it. The effect ends after ten minutes, when you use an action to dismiss it, or when your skeletal form is reduced to 0 hit points.
Price: 200 gp
Treasures From Heart of the Razor
5e Murder Crow: ? Murder Crow, Undead Monstrosity, Voracious Predator: ? Murder of Crows: When the murder crow dies, it explodes into a murder of crows. Encephalon Gorger Zombie, Vile Slasher: The Engineer worked tirelessly towards its purpose, wasting nothing. Using the corpses of its encephalon gorger crew as well as captured humanoids, it constructed gruesome and murderous servants.
This large, empty, cavernous compartment is a guardroom housing the reanimated remains of the Engineer’s crewmates, now his personal shock troops, called the “vile slashers” in Titus’ journal. Encephalon Gorger Zombie, Hairless Pale-Skinned Humanoid With Leathery White Semi-Translucent Flesh: ? Encephalon Gorger Zombie, Gruesome Murderous Servant, Personal Shock Trooper: ? Putrid Haunt: ? Undead Leech: ? Ghast: This storage chamber holds one of the Engineer’s more charming side projects. It keeps 6 ghasts created from the corpses of the crew of The Flying Fortune in this hold. Cadaver: A humanoid slain by [a cadaver lord's bite] attack rises 24 hours later as a cadaver under the cadaver lord’s control, unless the humanoid is restored to life or its body is destroyed.
A humanoid slain by [a cadaver lord's claw] attack rises 24 hours later as a cadaver under the cadaver lord’s control, unless the humanoid is restored to life or its body is destroyed. Cadaver, Undead Sailor, Gaunt Corpse With Wrinkled Leathery Skin Covered By a Thick Layer of Barnacles: Cadavers, undead sailors who perished in the perilous waters, prowl the rocks and reefs seeking to kill those who enter their territory. Through the millennia, the shores of Dolentla Island have seen their share of tragic shipwrecks, murderous mutinies and pirate melees. The unfortunate souls who lost their lives in these events haunt the island’s shores seeking to spread their miserable hate to the living.
The main cadaver force is led by Wily Roger, a vindictive captain marooned here ages ago by his mutinous crew. Set adrift in a small rowboat with four loyal crewmembers, the captain and his men died in the treacherous rocks and rip currents guarding the eastern shore. Wily Roger and his trusty band have haunted the waters around Dolentla Island ever since. Wily Roger, Cadaver Lord: The main cadaver force is led by Wily Roger, a vindictive captain marooned here ages ago by his mutinous crew. Set adrift in a small rowboat with four loyal crewmembers, the captain and his men died in the treacherous rocks and rip currents guarding the eastern shore. Wily Roger and his trusty band have haunted the waters around Dolentla Island ever since. Crypt Thing: ?
Hybrid trap (level 1-4, perilous, harm)
This 200-foot long, sloping corridor is filled with crushed skeletons and has a locked door at its lowest end. Above the door, spelled out in a mosaic, is a simple riddle. Answering the riddle makes the skeletons reanimate; a giant skull then falls from the ceiling and starts to roll toward the door.
Trigger. Uttering the answer to the riddle while in the corridor triggers the trap.
Initiative. The trap acts on initiative 20 and 10.
Active Elements. Hauntedwood Bowl reanimates the skeletons, then drops a giant skull into the corridor which rolls toward the bottom.
Reanimate Creatures (Initiative 20). 3 skeletons animate and attack living creatures in the corridor. The trap cannot animate more than 12 skeletons at a time. If it would animate more than 12, the oldest 3 crumble to dust.
Rolling Skull (Initiative 10). The first time this element activates, a massive skull drops from a trap door in the ceiling and starts to roll down the corridor at a speed of 50 feet a round. On subsequent activations, the skull moves another 50 feet down the corridor.
Skeletons (Initiative 10). The animated skeletons move and attack living creatures in the corridor.
Constant Elements. The massive skull barreling down the corridor threatens to crush everything in its path.
Giant Skull. Each creature in the skull’s path must make a DC 17 Dexterity saving throw. On a failure, a creature takes 10 (3d6) bludgeoning damage and is knocked prone. On a success, a creature takes half as much damage and isn’t knocked prone. Objects that block the skull, such as a conjured wall, take maximum damage from the impact.
Countermeasures. The trap’s trigger and active elements can be thwarted by particular countermeasures.
Trigger. A creature that succeeds on a DC 17 Intelligence (Investigation) check or DC 17 Wisdom (Insight) check can deduce or intuit the trigger word. A successful DC 17 Wisdom (Perception) check lets a creature notice the hidden trapdoor in the ceiling. The corridor has an aura of necromancy magic when viewed with detect magic; the mosaic has an rune of detection hidden in its design.
Reanimate Creatures. The door at the end of the corridor can be opened with a successful DC 17 Strength check, or a successful DC 17 Dexterity check using thieves’ tools. Once the door is open, the trap stops animating skeletons.
Rolling Skull. If the skull hits a barrier without destroying it, it stops. Once the skull hits the door at the lowest end of the corridor it smashes into smithereens. If it rolls out of the corridor, it crumbles to dust.
Magic trap (level 5-8, perilous, harm)
The floor of this dark cavern is uneven, and something crunches sickeningly beneath your feet as you enter.
Trigger (Produce Light/Darkness). Bringing or producing light, non-magical or magical, into the cavern triggers the trap.
Effect (Reanimate Creatures). Light reveals the bones in this room and they begin to glow with a sickly hue, animating into 8 skeletons that attack all creatures in the cavern. The skeletons will not leave the cavern, and they stay active until reduced to 0 hit points, or until 24 hours pass, at which point they crumble to dust. The skeletons can also be dispelled with dispel magic.
Countermeasures (Difficult). A creature that succeeds on DC 17 Wisdom (Perception) finds bone fragments scattered all around the room; with a successful DC 17 Intelligence (Arcana) check, a creature can discern the fragments are remnants of animated creatures. When viewed with detect magic, the room has an aura of necromancy magic.
With a successful DC 17 spellcasting ability check, a spellcaster can disrupt the enchantment on this room. Dispel magic also disables this trap.
Stewards of the Axe
Magic trap (level 17-20, moderate, harm)
At the far end of this chamber is an anvil, glowing with a throbbing, red heat. Stuck in the anvil is a rune-engraved battleaxe. Lying around the anvil are 4 dwarf corpses in various states of death and decay.
Trigger (Draw Weapon). Pulling the battleaxe from the anvil triggers the trap. It can only be removed by a dwarf.
Effect (Reanimate Creatures). The 4 dead dwarves rise as wights and attack all other creatures in the room, focusing on the triggering creature. If the creature that pulled the battleaxe from the anvil drops it or dies, the axe magically reappears in the anvil. The wights fade into nothingness if reduced to 0 hit points, or if dispelled with dispel magic (DC 18). They do not leave the room and, if not killed, return to dormancy after 24 hours.
Countermeasures. With a successful DC 12 Intelligence (History or Religion) check, a creature can identify the anvil and understands the trap. A dwarf has advantage on this check. If viewed with detect magic, the anvil has an aura of necromancy magic.
A spellcaster can disrupt the enchantment on the anvil with a successful DC 12 spellcasting ability check, or with dispel magic.
Magic trap (level 5-8, dangerous, harm)
The stench of blood dripping from an altar fills the air. The scarlet liquid seems to ooze from the stone by some magical means, flowing into cracks in the floor in a constant cycle. On either side of the altar are bronze statues of humanoids with open mouths, baring long fangs.
Trigger (Corpse). Bringing a corpse within 20 feet of the altar triggers the trap.
Effect (Reanimate Creatures). The corpse that triggered the trap is animated as a ghast that attacks any creatures in the altar room. The ghast will not go farther than 40 feet from the altar. It crumbles to dust if reduced to 0 hit points or after 24 hours.
Countermeasures. A creature that succeeds on a DC 15 Intelligence (Religion) check knows about the altar and understands the trap. The trap also has an aura of necromancy magic when viewed with detect magic.
A spellcaster that succeeds on a DC 15 spellcasting ability check can disrupt the enchantment on the altar, disabling the trap. Dispel magic can also disable the trap.
When the trap is triggered, it reanimates one or more dead creatures in the area to attack, block, or otherwise impede creatures. This effect requires some way to get a regular supply of dead creatures.
Like the Animate Objects effect, the reanimated creatures can be given a general command, such as to guard a particular chamber or corridor. Otherwise, the creatures mindlessly attack any other creatures in the area.
This effect could be used with a Corpse trigger; a body is brought into the area, and then reanimated when the trap goes off.
Effect. This effect turns piles of bones into skeletons or the corpses of Medium or Small humanoids into zombies. The number of creatures created depends on the trap’s lethality, as shown in the Creatures table earlier. If there aren’t enough bones or corpses in the trap’s area when it triggers, it still makes as many creatures as it can. This effect can create undead of higher CR if it’s severity allows.
Creatures reanimated by this effect stay active until reduced to 0 hit points, or until 24 hours pass, at which point they crumble to dust. The reanimated creatures will not leave the trap’s area.