Ophidosis Vulgaris

Suspected to be a disease of either divine or magical creation, Ophidosis Vulgaris is a progressive disease that affects the humanoid body in a number of possible ways. Although many brillaint minds have studied it, it remains incurable. Fortunately there are currently very few who suffer from the affliction, and its source is well known and well guarded. Even its modern existence is kept secret.

Vulgaris! For if you do not act now and fund our venture to solve this, it will spread through the population!

— Head researcher when challenged on the name

Causes

Aquiring the disease is directly related to interacting with the the stone relic at the center of the Valley of the Broken Egg. Currently no other origin of the disease is known, however some victims have been able to transmit the infection through various means.

Why the Broken Egg imparts this condition is unknown. The origin of the relic is lost to time, even to the High Elves of the Wildewoods. To prevent further infection, it's location has been hidden through many magics and what mentions there were culled from the records. When it was found even powerful magics only temporarily alleviated symptoms, this was chosen as the best response to prevent further infections.

Symptoms

Symptoms vary from person to person, but initially include sensitivity to light, dry-scaly skin, irritability, and lethargy. Within a day or so of contact, the subject will develop a fever. From that point changes progress rapidly as the body begins to mutate. This can be as simple as dry skin patches developing into snake-like scales or far more severe such as developing serpentine eyes or a forked tongue. The fever will receed at the emergence of this first feature but further mutations continue to occur.

It has also been noted that those who have developed fangs or forked tongues in the early stages of the disease can spread it. The forked tongue seems to also affect the salivary glands so that subjects saliva is able to spread the contagion, which subjects able to spit in an imitation of certain snakes. Similarly a bite from the fangs has been recorded as infectious.

Treatment

Application of Lesser Restoration magics halts the progress of the disease for 24 hours. Greater Restoration will remove one symptom and halt the progress for 24 hours. No cure has been found.

Prognosis

While hearty individuals may fight off the disease for some time, or those capable of great magics may be able to halt its progress for awhile, the final prognosis is transformation. A small number of these are terrible and deadly, the disease taking a final fatal turn. Most of these follow a few specific patterns. But none are able to remain in civilized society.

Type

Physiological

Origin

Divine

Cycle

Chronic, Acquired

Rarity

Extremely Rare

Initial Infection

Most infections happen through contact with the Broken Egg. Should someone touch the Broken Egg, everyone withing a 15' radius must make a DC 18 Constitution saving throw or become infected. Other vectors are, such as infected fangs or spittle, are easier to resist with a DC 15. Typical first onset symptoms will happen within moments of becoming infected including gaining a level of exhaustion that can only be removed through a Lesser Restoration or similar magic. 24 hours later the infected will develop a fever.

Tracking Mutations

The Pureblood Characteristics table in Volo's Guide to Monsters can be used to determine mutations. The initial mutation should occur 1d4+1 days after infection. Following that, the subject should make a DC 13 Constitution saving throw every night. On a failure, again use the Pureblood Characteristics to determine a new mutation except on a roll of 19 or 20, instead of rolling again, use the Yuan-Ti Mutation Evolution table to determine the final, permanent mutation.