Falsification

Very few are susceptible to the horror of falsification, but the darker parts of the Shadowfell are teeming with these stubbornly powerful critters with a seemingly endless lifespan. Creatures with this condition are called "falsified," or sometimes "fell."
At one point in Agrophon's history, these poor souls were called "sorrowsworn," but some of them are more complicated. In some ways, the sorrowful ones are the least unnerving.

Transmission & Vectors

Falsification has a small chance to propagate across whole populations. If someone witnesses a creature transform, they have to resist a similar change in themselves. A creature might also turn after a near-death encounter with fell creatures.

Causes

Creatures in a deeply vulnerable state may succumb entirely to the airs of the Shadowfell, which mold them into horrific caricatures of their physical and mental qualities.

Symptoms

The falsified are distorted monsters of all sorts, from scurrying critters to mountainous beasts. Hostile or not, they tend to be exceptionally strong, able to lift several times their body weight, like ants. They sometimes pursue creatures they find interesting; the best way to evade them is to move slowly and quietly, with a boring gait.
While a person is being falsified, they might feel like they're wasting away, but their bodies aren't weakening or reducing. Instead, they're being replaced by new material, which acts beyond their control. The original person seems to deteriorate into nothing, even though they still feel themselves moving, often stronger and faster than before. This fall can happen over several days, though extreme events can cause it to happen in minutes.

Treatment

Once the transformation starts, it cannot be reversed except with a Wish. Greater Restoration has a slight effect on them, restoring a bit of memory and self-awareness, but most fell creatures resist the spell.

Prognosis

Most of the falsified act completely by instinct, but their old consciences are still sealed inside and might resurface. Some of them keep or regain the ability to speak.

Prevention

Falsification can be prevented through the safer forms of Shadowfell influence. A Shadow Form grants immunity to all further influence, and people with Shadow Nature protect those around them.
The easiest way to prevent falsification is to exercise one's wisdom. This isn't as difficult as it sounds, but some people's attempts at it are dangerously misguided.

Cultural Reception

For some, the falsified are so horrifying that no place which contains them is safe. For others, the falsified are a common sighting on the edges of civilization, but they're usually harmless when left alone. A few organizations, including the Signeadown, are determined to kill them whenever possible: they believe that the people trapped in those horrific bodies must be freed, and there's only one way to do it.
The falsified inspire a primal fear in nearly all other creatures. This fear cannot be entirely cured except by Shadow Nature.

Type

Magical

Parent

Shadowfell Influence

Falsification

6-level Necromancy (ritual)

Casting Time 1 Hour

Range Touch

Duration Instantaneous

Components V, S

This effect is an extremely rare hazard of the Shadowfell, or the result of a Shadow Form or Shadow Nature spell being terribly misperformed. The target must make a Wisdom saving throw; on a failure, they begin the unstoppable transformation into a falsified creature. A creature living in the Shadowfell must make this saving throw, with advantage, once every 10 years or so. However, some events (such as a traumatic encounter with fell creatures) may cause the saving throw to be triggered immediately.
The base DC for the saving throw is -2, so failure only occurs in extreme circumstances. In places with wilder climates and denser shadows, the DC may increase up to 1. Powerful necromancy can briefly increase the DC as high as 10 in a small area. Creatures with Shadow Nature can protect those nearby, reducing the DC by up to 10 for one creature, 9 for two creatures, 8 for four creatures, 7 for eight creatures, and so on.

Immediate Effects

While transforming, the creature must make a Charisma saving throw each round, with the DC starting at 10 and increasing by 1 each round. On a success, the creature stays in control. After 5 failures, the transformation is complete.
Falsified creatures have massively improved Strength, an Intelligence of 6 or lower, and the hit points of a creature five levels higher (to a maximum of CR 20). They also accrue a series of adaptive mutations during the transformation: for example, they might gain fireproof skin if someone tries to burn them, and they might become proficient climbers if they're trapped under a ledge.
Falsified creatures instinctively try to resist magic, even if no saving throw is listed: when targeted by a spell like Cure Wounds or Guidance, they will make a Charisma saving throw, resisting the spell on a success.

Class(es): Wizard