Summary: A genetor’s hidden enclave is host to a powerful bioweapon that can mimic creatures’ anatomy and behavior, even humans or xenos, with quite some fidelity. It’s extremely biologically adaptable, based on the space marine omophagea organ and polymorphine. A small piece of it has gotten loose and is now rapidly consuming biomass and mutating in secret, harvesting more knowledge of the facility and the outside world with each being it consumes.
Discovery: Though well-camouflaged from a distance, characters who have discovered this encounter have come close enough to clearly see the genetor enclave is artificial. Large doors built into the side of the hill are painted in a camo pattern, and a satellite dish on the top is disguised with fake branches and more camo as a tree. The illusion is not convincing anywhere within fifty meters of the facility. The door requires a Hard(-20) Security check to unlock, has 16 AP and requires 10 damage for a human-sized hole to be cut in.
A Challenging(+0) Awareness check while searching the hilltop will reveal an exhaust shaft hidden under a camouflage net. If the characters have any kind of infrared or other means of detecting heat from a distance, searching the hill automatically turns up the existence of the vent as it periodically blasts out intense heat. The thin grating on the exhaust shaft has only AP 4 and is completely destroyed after only 5 damage. Characters attempting to enter through the exhaust shaft must roll 1d10, and on a roll of a 1, are hit with a blast of 1d10+4 energy damage with 7 penetration as the facility vents exhaust.If, for some reason, characters do not move directly from the exhaust vent into the facility, but instead stay in the vent for a while, keep track of the d10 rolled. Every 15 seconds or so (real time) one or more characters spend hanging around the vent, move the die so that the face one point lower is facing up (i.e. 7 to 6, then 6 to 5, and so on). When it reaches zero, the facility vents exhaust. If the facility’s power generator has been shut down or destroyed, this exhaust vent will no longer be hazardous.
Exploration: The facility contains five (living) characters. The genetor is in the command room, where he’s barricaded himself in, and can see characters on the cameras spaced throughout and communicate with them using the intercom. There is one camera in each room, and they don’t have a perfect view of all spaces, so it is possible to sneak through without the genetors’ notice. It is also possible to disable a camera with a Challenging(+0) Security check. The genetor will communicate with anyone he sees enter the facility via intercom and claim that he can’t hear them in response. This is a lie, and anyone who suspects as much can confirm it with a Difficult(-10) Scrutiny test.
The genetor will tell any intruder in the facility that a monster is loose in the facility with the power to assume a human form, and that no one in the facility is to be trusted. If anyone of the characters is out of sight for even a moment, they too could be replaced by this shapechanging creature. The genetor will claim the creature was set free by his assistant, who has gone mad, and ask the characters to destroy it. If they breached the front door to get in, the genetor will immediately demand that the characters seal it up, before the monster escapes (he will demand this before even explaining what the monster is).
Ultimately, the genetor wants the players to kill the monster, but also to be killed themselves, along with everyone else in the facility except for the genetor himself. The genetor isn’t very impressive physically himself, so he’ll try to keep the characters from confronting the monster until after its had a chance to devour a few people, preferably at the very least the genetor’s rogue assistant (and the genetor doesn’t even know for sure that his assistant isn’t actually the monster in disguise). Once the creature has bulked up, he’ll let the characters fight it to the death, then step in to kill whoever’s left over. If the characters win without much difficulty, the genetor will content himself with asking them to keep the AdMech’s secrets secret and promise them a favor in return for their assistance and discretion.
The genetor’s assistant patrols the corridors with a flamer. Upon meeting any living creature, he will threaten them with the flamer and demand their immediate surrender. He has an aggressive personality and disposition of 15 to start, largely because he is paranoid that any living creature besides himself may be the monster. If the characters successfully convince the assistant that they have been within sight of one another since arrival, his disposition towards them will immediately increase by 20 points, up to a maximum of 50. Other methods of increasing disposition can still increase it to above 50, however at 50 disposition the assistant is already reasonably convinced that none of the characters are the monster. The assistant says that he’d tried to warn his master of the danger of experimenting directly with the Emperor’s work with space marine organs, and now that it’s all gone horribly wrong his master is trying to pin the whole thing on him. He’ll request the characters’ help in breaking into the command room to kill the genetor, then setting the facility’s reactor to overload and leave, sealing the door behind them, leaving any surviving skitarii behind to be vaporized along with the monster, mainly because the assistant thinks one of the skitarii probably is the monster, though he isn’t sure which one.
The skitarii have bunkered down in the armoury. There’s three of them, and they’re all getting more paranoid with each day. The skitarii sergeant (disposition 30, confident personality) isn’t convinced the monster could incorporate stolen cybernetic implants into its form without consuming the genetor or his assistant, and that the monster has probably taken the form of a small creature like a rat and is biding its time. The corporal (disposition 25, aggressive personality) thinks it’s taken the assistant’s form and is trying to persuade the sergeant to kill the assistant and burn his corpse. The surviving private (disposition 30, submissive personality) has no idea who the monster might be, and is growing more and more jittery and trigger-happy all the time. His paranoia is not particularly logical, and he is more and more worried that the monster might be one of the other skitarii. The two NCOs take a dim view of his overly emotional view of the situation, and consider him, barely augmented as he is, incapable of grappling with the situation reasonably. They’re both careful to keep an eye on him, as the monster would have an easier time mimicking him and his mostly fleshy body than anyone else in the facility.
If the plot begins to stall, have the creature find and ambush the assistant or the genetor, whoever is currently out of the players’ sight, and take over their body. At this point, the monster will try to kill everyone else in the facility and make sure nobody knows it exists so it can move into human society without any fear of detection.
Confrontation: The skitarii captain is right. The monster is currently hiding out in maintenance ducts as an oversized rat of Puny(2) size. It killed one of the skitarii when it first escaped and attempted to use its ability to consume memories and knowledge to mimic the skitarii’s personality, but it was caught by genetor’s assistant and torched with the flamer, whereupon it was forced to shed quite a bit of biomass to survive, losing significant data stored in the junk DNA of that biomass. It retains knowledge of basic human functions, but cannot understand language or operate complex machinery. The genetor’s assistant is also partially right, in that the creature doesn’t understand nearly enough AdMech lore to actually integrate their implants effectively into its anatomy, but it can position them in the right spot to look the same and then just plug them into what is basically a giant cancerous tumor hidden underneath its skin, and thus the implants are completely non-functional. Mechadendrites will be limp, cyborg limbs will be frozen in place, bionic eyes will be completely blind, and so on. If the creature absorbs either the genetor or the assistant, it will be able to actually use any implants it finds, and indeed will have no difficulty attaching them to its extremely morphic anatomy.
The creature can acquire new skills by devouring brains, and can absorb biomass by consuming it, then shapeshift with this biomass into an entirely new organism. If the creature eats someone alive, its Intelligence, Perception, Willpower, and Fellowship scores will rise to match the devoured character’s scores if they were higher, it will absorb any skill trainings the devoured character had if they are higher than its current skill trainings, and will additionally gain any talents the devoured character had. The creature also gains points of size equal to one less than the devoured character’s own size trait, up to a maximum of two size points bigger than the devoured creature. For example, if the creature is Puny(2) and eats a full grown human (size 4), it gains three size points and can grow up to Hulking(5). If the Hulking(5) creature then ate a Scrawny(3) creature, it would not grow, because it is already two size points larger than the Scrawny(3) creature, however it could still absorb mental characteristics, skill training, and talents from the Scrawny(3) creature.
For each size point past 1, the creature may have one of the following traits: Amphibious, Brutal Charge, Burrower, Crawler, Dark-Sight, Deadly Natural Weapons (requires Natural Weapons), Fear(1), Flyer, Multiple Arms, Natural Armour, Natural Weapons, Quadruped, Sonar Sense, Toxic, Unnatural Agility, Unnatural Strength, or Unnatural Toughness. Its unnatural characteristics start at 1 and may be increased by 1 for each trait sacrificed, so, for example, at Average(4) size the creature gets three traits, and may have Unnatural Strength(3), or Unnatural Strength(2) and Unnatural Toughness(1), or Unnatural Strength(1), Unnatural Toughness(1), and another trait like Natural Weapons, and so on. The creature does not gain any automatic bonus to its unnatural characteristics for being very large. The square-cube law is a harsh mistress. Regardless of other traits, the creature always has Regeneration equal to its current Size score. The creature can rearrange its current biomass to change which traits it has as a full action.
The creature can shed biomass as a full action at any time, stepping out of its skin and leaving behind a shed skin and possibly some bones or traces of organs, as well as plenty of blood. This mass can then be reconsumed later, provided it remains intact. If the creature wants to take someone’s place, they will devour them entirely and turn into a large, grotesque monster, then shed the extra biomass and store it. The skin of the misshapen monster is not recognizable as anyone, which means that even if the shed biomass is discovered, it will not be clear whose form the creature has taken. Whenever the creature sheds biomass, it must lose at least one point of size. The creature may choose to heal all wounds, including critical wounds, by sloughing off a size point’s worth of biomass, however this biomass is then too badly damaged to be reassimilated later, but is instead permanently lost. Whenever the creature loses a point of size, it loses five points in each characteristic along with it, and for each size lower than Average(4), the maximum its skills can be trained to decreases by one step, so at Average(4) it can go up to +30, but at Scrawny(3) it can only go up to +20, and at Puny(2) only to +20, and so on. Likewise, at Scrawny(3) it loses all tier three talents, at Puny(2) it loses tier two, and if reduced to Miniscule(1) it loses all talents altogether.
The creature cannot split its consciousness between multiple forms. It can be a maximum of one contiguous creature at a time. All of its body parts must be connected to a brain by a neural system to operate, so anything severed will cease functioning and any attempt to split into two monsters joined by the same consciousness will fail. The creature can clone itself by creating a separate brain and then splitting that brain off into a separate body, however after the split both creatures are separate individuals. One will not automatically know what the other does, nor will they necessarily even be friends or allies. Both of them want the same thing – to join human society without humans knowing about them – but if, for whatever reason, only one of them can do so, they will fight over it, and likewise one may attempt to sacrifice the other and the other will not appreciate that. They may fight over biomass, especially if they have both been reduced to a small size and rejoining would allow them to get back to human size, thus leading to them fighting to devour one another in order to be the surviving consciousness of the merge. Because of all these complications, the monster will avoid cloning itself if it can, preferring to make itself bigger or create more masses of spare biomass for later reassimilation rather than creating potentially dangerous clones.
Rewards: Allying with the creature longterm is probably tech-heresy, but even Imperium-aligned characters might consider it. The creature’s psyche is mostly made up of what its eaten, so it will, for the most part, have the goals of the Adeptus Mechanicus, unless it’s consumed multiple player characters or NPC allies they brought with them from outside. The creature has little use for biomass that will make it grow too large to blend in easily in Imperium territory, and even in Chaos territory where this blatantly hyper-mutated creature is only slightly out of the ordinary, it’s plainly impossible for the creature to get to larger than Enormous(6) size by consuming Average(4) humans. There’s not exactly a large supply of ork nobs or space marines around to nom on, so the creature has little reason to go hunting once it’s eliminated anyone who knows what it is and actively wants to kill it. Instead, it will likely dedicate itself to recovering archaeotech from the fallen Age of Strife civilizations of Vestitas Antiqua. It may even try to impersonate the genetor or his assistant in order to become part of the Adeptus Mechanicus, though it would be just as happy to go rogue as a heretek considering the AdMech tried to kill it pretty much as soon as it began to live.
If the characters side with either the genetor or his assistant and kill the other, they’ll have a friend in the Adeptus Mechanicus (provided the fight with the monster doesn’t weaken them enough to be finished off by the genetor) who owes them a favor. They won’t call in a titan legion or anything, but the AdMech could certainly provide and install some cybernetics or provide some rare modifications to some equipment. These would be one-time favors, however, not an ongoing service.
If the characters are the only survivors (or, for that matter, if they end up allying with the monster), the facility can be used as a decent hideout in the area. It has an extremely well-stocked medlab with a supply of advanced medi-kits providing +20 bonuses to Medicae checks that will essentially never run out (there are something like 100 medi-kits’ worth of medical materials in the lab – if that number of medi-kits are lost or destroyed in the course of even a very long campaign, you’re doing it on purpose).