Infernal Machine Rebuild hopefully provides plenty of options for you to run the adventure the way that works best for your campaign. But if you’d like to customize this adventure even further, consider any of the following possibilities.
Chapter 1: The Unicorn and the Hags
The conflict between the hags and the unicorn Banrion can be complicated or augmented in a number of ways.
Clandestine Hags
If having three dryads working together is too immediate a tipoff that these might be hags forming a coven, you can add a fourth illusory mother to the mix to help allay suspicion. Created from a few logs and branches, Mother Hedgehog sits quietly in the corner of the cottage. If the characters attempt to speak with her, the programmed illusion is able to mumble a few incoherent words. A successful DC 16 Intelligence (
The hags' cottage is built from three trees entwined together. These trees might contain the three true dryads whose appearances the hags have stolen for their own use, and who have been enslaved by the hags to help with their corrupt gardening. If the characters treat with Banrion, the unicorn asks them to help free the dryads to set the woods back to order.
Instead of the hags being disguised as goodly dryads, you might instead choose to reverse the scenario. The Three Mothers might really be dryads in need of help, with Banrion the unicorn an evil creature that must be defeated to save the woods. The unicorn might even be using its dark magic to cause the dryads to appear as hags.
Unicorn Showdown
If the characters initially make an aggressive approach toward Banrion (whether because the hags have fooled them or because the unicorn is evil), you can make the fight tougher by having the unicorn appear while the characters are attempting to cross the clock tower bridge. While fighting on the bridge, Banrion looks to knock characters off the tower into the chasm below, or even to try to collapse the tower under the characters while she teleports away.
If the unicorn later makes peace with the characters, she teleports down into the chasm (if still able to) and heals them.
Chapter 2: An Invitation Extended
Meeting with the infernal agents has the potential for a number of interesting story options.
Updated Guides
As written, the mechanical guides can safely teleport the characters to and from the specific adventure locations. If it fits with your campaign, you might opt to allow teleportation to other locations in time and space with a successful DC 20 Intelligence (
You might decide that neither agent would ever allow the components they already possess to leave their sight, or that the characters are the first ones to have come across any missing components. If so, Lynx’s guide is powered by a dangerous combination of living
Healthy Competition
When the characters make their choice of which agent they want to work with, whatever agent they turn down immediately arranges to send out their own competing expedition. (If the characters agree to work for both agents, both agents might still send out second redundant expeditions as insurance.)
These expeditions are composed of five cultist servants, led either by the enhanced medusa for Lynx, or the brains in iron for Sir Ursas (see below for more information on both). Each expedition also has its own mechanical guide. You might use the members of the rival expedition to chase after the characters, or they might have already arrived at one of the locations and be set up for the characters to stumble upon. The members of the alternative expedition might set obstacles along the way, possibly inspiring the characters to do the same. Using the power of a mechanical guide might allow for the creation of particularly devious traps that can be set across space and time. And the members of the alternative expedition certainly look to sabotage or destroy the characters' mechanical guide in order to strand them.
These competitors might succeed in securing some of the missing components, whether they steal them out from under the characters or take them directly in combat. Any stolen components will be delivered to their respective agents before the characters return from the past.
Enhanced Medusa
Like the enhanced sphinx from Lost Laboratory of Kwalish, this creature has been augmented with various technologies from the Barrier Peaks. Specifically, its eyes have been replaced with mechanical frames into which it slots different lenses. This is the same magical technology that was used to create another artifact, Daoud’s Wondrous Lanthorn. The medusa is nicknamed “Daoud’s Living Lanthorn” as a result.
The enhanced medusa uses the medusa stat block with the following changes:
- It has
truesight out to a range of 60 feet. - It can cast the
light cantrip at will. - Its Petrifying Gaze trait turns creatures into metal, wood, or porcelain (the medusa’s choice) rather than stone.
If this adventure is played as a sequel to Lost Laboratory of Kwalish, the enhanced medusa might seek revenge for what befell its ancestor Gloine Nathair-Nathair, or could be appeased with information regarding that medusa’s whereabouts.
Who’s Who
While little is known of Daoud, his lanthorn was part of the treasure to be recovered in the AD&D adventure module Lost Caverns of Tsojcanth. Light cast through the different faces of the lanthorn created different magical effects, which the lanthorn fueled with crushed gemstones.
Brains in Iron (The Council)
This creature originated from old designs of Kwalish, and takes the form of multiple brains that have been magically preserved and which collectively operate a new mechanical body. The brains share insights and knowledge with one another, and have typically been taken from creatures that desired to prolong their consciousness—or that were tasked with controlling a construct for all time as punishment.
A brain in iron uses the brain in a jar stat block with the following changes:
- It is lawful neutral.
- It has the construct type.
- Its size is Large.
- It has Armor Class 15 (natural armor).
- It has a speed of 20 feet.
If this adventure is played as a sequel to Lost Laboratory of Kwalish, this creature began as the brains in jars encountered in the Barrier Peaks. After constructing a new collective body from spare parts, the brains escaped (and now seek revenge against the characters if they did not aid the brains sufficiently during that adventure). The brains' collective goal in seeking the missing components is to be able to transfer themselves into the ultimate mechanical body—the Infernal Machine of Lum the Mad.
Chapter 3: Construction of Horrors
You can expand the characters' exploration of the Tomb of Horrors construction site in a number of ways.
Hanging with Moghadam
Even villains have their hobbies—and for Moghadam, that hobby is death traps. Any character who discusses traps with Moghadam can impart to him a new deadly design—either using suitable roleplaying and player ingenuity, or a successful DC 16 Charisma (
Muralist Mutiny
As written, the sculptors in the Tomb of Horrors are eager to escape but the muralists are loyal to Moghadam. However, you might decide that the muralists have their own reasons to flee servitude, and have secured a set of
Rock and Ruin
As an added element of danger and dilemma during the ceremony in the chapel (area area 14), each time a character succeeds on a saving throw to resist the ceremony’s power, one of the worshipers in the pews is overcome and transforms into black rock.
If the black rocks from the chapel are brought to the sculptors, you might decide that they can help restore those victims to life using their superior mason’s tools. Alternatively, the sculptors might want to incorporate these magic rocks into an even more impressive golem, helping to ensure their escape. Likewise, if taken to the Temple of Moloch, these rocks might be highly prized for the crafting of statues and homunculi.
Go to Hell
The fiery rift of area 16 allows Tarnhem to return to the Abyss. But depending on the setup of your campaign (and particularly if you are playing through Baldur’s Gate: Descent into Avernus), you might instead have this rift lead to the Nine Hells. There, Tarnhem joins the demonic horde taking part in the Blood War.
If the characters later travel through Avernus, they might encounter Tarnhem there—with his reaction to them depending on their interactions at the tomb.
Chapter 4: Temple of Moloch
The level of chaos and creative power on display in the Temple of Moloch lends itself to a number of play options.
Trade Talk
Thessalar’s fixation on monster design provides an opportunity for bonding with any character with insight into that topic—or who can fake it well enough, either using suitable roleplaying and player ingenuity, or a successful DC 16 Charisma (
Tressym Patrol
Considering the variety of laboratory creatures residing in the temple, its hallways might also be populated by roving packs of wild, escaped tressym. These flying cats follow and spy on the characters, but might help lead them to various locations (such as the secret door outside area area 38) if treated well. The tressym despise Barbatos’s hell hound (area areas 12 and area 13), and actively aid any effort to destroy it.
Mixing up the Thieves
If the characters pass through the village mentioned in the “area Temple Approach” section, they might discover that one of the villagers is one of Mack Francache’s thieves, left behind to keep an eye on activities outside the temple. When the characters arrive, this thief presents themself as a seemingly reluctant guide willing to join the characters on the incursion into the temple. While there, they secretly try to direct the characters toward rescuing the imprisoned thieves.
Mack Francache the wererat prisoner (area area 9) might instead be a lycanthrope of some kind never seen before: a weremouse, a weremoose, or even a wereooze. Thessalar is extremely interested in studying this new lycanthropy. Alternatively, Mack might have been a normal human when he came to the temple, only to have Thessalar impose this strange lycanthropy upon him.
Statuesque
You might introduce different options for interacting with the statues in area area 24, especially if combat breaks out there. For example, if the eidolon inhabits a statue of Zariel or Bel, the characters might gain advantage on attack rolls against that statue if they serve the archdevil’s agent (or disadvantage on attack rolls against the statue of the competing agent’s patron). Out of combat, if the characters are allied with Moghadam and remove a hand and an eye from any statue, Vecna rewards them with some boon (advantage on attack rolls during the first round of their next fight, having a consumable magic item appear in the statue’s remaining hand, and so forth).
Secret Chicken
One of the chickens in area area 35 might be one of Thessalar’s experiments, such that it occasionally lays silver eggs (worth 10 gp) or even golden eggs (worth 20 gp). In this scenario, both boggles originally came to the temple to steal this chicken. Or this might just be a tale the remaining boggle tells, planting false eggs with the chickens in order to better negotiate with the characters.
Chapter 5: Final Showdown
The presence of a legendary artifact in the final chapter of the adventure opens up lots of possibilities.
An Infernal War Machine
For deeper integration with Baldur’s Gate: Descent into Avernus, an alternative climax could have the characters' chosen agent complete their version of the Infernal Machine—which is then converted into an infernal war machine. Such a process might involve drawing on other elements of the adventure’s locations (the Tomb of Horrors' still-to-be-built stone juggernaut, the skeleton of the thessalkraken, and so forth) for use in the war machine’s chassis.
The characters are then asked to drive the war machine into Avernus, to confront the minions of the archdevil opposed by their agent and thwart that archdevil’s plans. Alternatively, the Infernal War Machine might be teleported to the Nine Hells, where the characters later encounter it during the course of Baldur’s Gate: Descent into Avernus and are required to stop it.
A Mighty Servant
When the characters deliver the missing components to their chosen agent and the other agent launches a raid, that raid is led by a second artifact that the agent has been constructing—the Mighty Servant of Leuk-O. Alternatively, if Kwalish is involved, he might build or upgrade a suit of powered armor (from Lost Laboratory of Kwalish) to become the Mighty Servant of Leuk-O. The characters can then use that artifact (with features determined by you) to counter the Infernal Machine of Lum the Mad.
Additional Locations
You can turn this adventure into an entire campaign by adding additional locations containing more missing components of the Infernal Machine. Just as the Tomb of Horrors was repurposed here, you might similarly repurpose other adventures from D&D history or your previous campaigns, manipulating their time lines to create alternative scenarios.
So many of the iconic locations in D&D would make great additions to this adventure, from the tower of Sorcere in Menzoberranzan, to one of the elemental nodes in Princes of the Apocalypse, to the level of Dweomercore in Dungeon of the Mad Mage, to Skyreach Castle in Hoard of the Dragon Queen. A few specific examples are presented here.
Tomb of Annihilation
Missing components could be hidden in any number of locations in the jungles of Chult, including the Lost City of Omu, or even integrated into the Tomb of the Nine Gods. For example, to recover a component located at the City of Omu’s amphitheater, the characters might need to overcome the King of Feathers at some point in the past (making it a younger, weaker tyrannosaurus rex) or the future (where it has become a deadly dinosaur zombie).
Glacial Rift of the Frost Giant Jarl
Missing components could be hidden throughout many areas of this adventure from Tales from the Yawning Portal. In the caverns of area 5, components could be buried within the ice in a way that requires the characters to access them in the past—and allowing the creatures trapped in the ice to be brought back to life. In the visitors' cave of area 26, components might have been brought as special gifts by past dignitaries unaware of their true nature. And in the snow-covered dome of area 28, they might be guarded as treasure by the remorhaz.
White Plume Mountain
The characters might need to travel back to a time when Keraptis first constructed his legendary dungeon (featured in Tales from the Yawning Portal), and used components from the Infernal Machine of Lum the Mad to magically secure
If you are playing this adventure alongside Lost Laboratory of Kwalish, White Plume Mountain offers a number of connections to that adventure’s guides. Ctenmiir the vampire once haunted White Plume Mountain, while Mary Greymalkin’s former tutor, the witch Thingizzard, dwelled nearby.
Additional NPCs
To let the characters dig even deeper into the world of the adventure, you can also consider adding a few more iconic NPCs.
Acererak
During the time frame in which the characters visit the Tomb of Horrors, Acererak is still a mortal human spellcaster—albeit an incredibly evil and powerful one. You can play him as an archmage—or for higher-level parties, use his stat block from Tomb of Annihilation, but without his undead traits, his Rejuvenation and Turn Resistance traits, and his Disrupt Life legendary action. Acererak does not reside in the Tomb of Horrors at the time the characters travel there in chapter 3, but he might appear if its construction is hindered. He is keen on preventing characters from utterly destroying the tomb, but might grace them with an audience if they look as though they could prove useful to furthering his plans.
If enmity arises between the characters and Acererak, the would-be lich is a formidable foe. You might make this special version of Acererak even more so by having him wielding a sword with a
Mary Greymalkin
A potential guide in Lost Laboratory of Kwalish, Mary Greymalkin might appear in this adventure as a servant of Moghadam or Thessalar, a guide for the thieves who entered the Temple of Moloch, one of either agents' couriers, and so forth. As she does in Lost Laboratory of Kwalish, she offers to let the characters draw from her deck of several things. Some of the deck’s cards bestow effects more relevant to this adventure, as follows:
Donjon
You are instantly teleported to and confined within either the Tomb of Horrors (in area area 7) or the Temple of Moloch (in area area 10) as the DM determines. Everything you were wearing and carrying stays behind in the space you occupied when you disappeared. You draw no more cards.
Flames
A powerful artificer (Moghadam or Thessalar, at the DM’s determination) becomes your enemy. The artificer seeks your ruin, savoring your suffering before attempting to slay you.
Gem
One of the 1,000 gp gems shaped by Seodra the gemsmith (see area area 18a of chapter 3 or area area 31 of chapter 4) appears at your feet. If all those gems are unavailable, you gain an equivalent hoard.
Knight
You gain the service of one of the servants of your chosen agent (see chapter 2), who appears in a space you choose within 30 feet of you. The NPC serves you loyally for the duration of the adventure, understanding that the fates have drawn them to you. However, they remain violently opposed to any servants of the opposing agent. You control this character.
Ruin
All forms of wealth that you carry or own, other than magic items, are lost to you. This wealth can be recovered either in the Tomb of Horrors (held by Moghadam in area area 1) or the Temple of Moloch (locked in the treasure vault, area area 38), as the DM determines.
Talons
Every magic item you wear or carry is lost to you. These items can be recovered either in the Tomb of Horrors (held by Moghadam in area area 1) or the Temple of Moloch (locked in the treasure vault, area area 38), as the DM determines.
Throne
You gain proficiency in the
The Void
This black card spells disaster. Your soul is drawn from your body and held within a soul gem in the Temple of Moloch (with the gemsmith in area area 31). While your soul is trapped in this way, your body is
Tuerny the Merciless
This lawful evil male human archmage is no longer at the Tomb of Horrors, but contributed to the construction in his own way. Acererak hired Tuerny to install magical technology obtained from the Barrier Peaks into the tomb (including the missing components), which now hold Tarnhem imprisoned here and drain his life force. Since leaving the tomb, Tuerny has used what he learned in crafting Tarnhem’s prison to create the first of his fabled