Yahtzee

The Source of the Infection, Also referred to as "The Mother" - A host of fungi, colonies of slime molds, mushrooms, and mildew stretch across the hide of this dragon- it's unclear if her mind is still in control, or if there's nothing left up there but cordyceps spores. Unlike her sea-faring brethren, Yahtzee can be found in putrid swamps, preferring the murk of the mire to the clarity of the sea. She spends much of her time mostly submerged in the muck, the colonies on her hide thriving in the moisture and humidity. Despite her hulking size she can be hard to see coming, shrouded as she is in layers of fungi and rot. Fathoms weren't built for the confinement of the wood, but she gets around just fine, and what could at first glance be a fungus covered crag may actually be Yahtzee looming in the shade. If you come across her while wandering the forest it's best to give a wide berth, a touch of her claws can embed roots of fungi underneath a dragons' scales, and it would be unwise to breathe in the haze of spores surrounding her, raining down onto the forest floor with every staggered step, leaving pinpricks of young fungi on the ground behind her, mycelium snaking through the peat.


Infection:
Spreads through spore inhalation or physical contact with Yahtzee. Physical contact spreads faster but is more curable, spore inhalation is slower but more thorough, harder to notice at first and is often too late when discovered.
Contact:
When a dragon is touched by Yahtzee, threads of Mycelium instantly snake under the scales of whatever she is making contact with - taking root. After a few days mushrooms (or other types of fungus) will sprout, slowly spreading out from the initial point of contact. If caught early, careful removal of the fungi and mycelium threads can cure the infected dragon, but it's a small window, and any missed mycelium will continue to grow and spread throughout the host. Fungi will slowly overtake the host's body and eventually mind, until all the only thought in their head is to make their way back to the woods, and to Yahtzee, using their last remaining bodily function to get to her before giving out. Her fungi will "reclaim" their corpse.

• Symptoms: begins with noticeable fungi growth around the site of infection, the fungus growing from the dragon will grow in size and spread more the longer the dragon is infected. Feeling itchy underneath their scales, the itchy feeling will grow maddeningly incessant as the infection progresses (in the latest stages of infection they stop feeling it). Mycelium will slowly take over the nervous system, making movement more staggered and speech more difficult, they will lose consciousness the more the infection progresses as it takes over their brain.

Spore Inhalation:
A cloud of spores surrounds Yahtzee, and if enough are inhaled, a dragon can become infected even if they haven't physically touched her. The infection is slower, as the spores grow and form mycelium, but it's nearly impossible to remove, as it quickly spreads out through the lungs and into the nervous system, eventually reaching the brain. The same process then happens as with Contact, the mycelium will spread through the host's body, eventually fungi sprouts from the dragon's body, and their mind will eventually be overtaken until they make their way back to Yahtzee.

• Symptoms: begins with slight difficulty breathing and development of a cough. Feeling incredibly itchy underneath their scales, faster and more severe than infection with contact, the itchy feeling will grow maddeningly incessant as the infection progresses (in the latest stages of infection they stop feeling it). Fungus will eventually begin to sprout all over the dragon's body in mid-late stages of infection, clustering most densely around their chest. Mycelium will slowly take over the nervous system, making movement more staggered and speech more difficult, they will lose consciousness the more the infection progresses as it takes over their brain.

Infected dragons can be contagious through contact, but not nearly as high a chance of being infected as contact with Yahtzee. Once a dragon is infected, the fungus's urge to spread is not as strong as its want to return to its original host, Yahtzee, so the mother colony may feed. All cases of dragons where the infection has failed to be removed early on have been fatal.
As of right now infected dragons have not been known to be aggressive

Origins:

Yahtzee used to be what you expect from a Fathom, a wandering sea-faring dragon traveling with a pod, following the ocean currents and thriving in the depths of the sea. Her and her pod were flying over a stretch of continent when a storm hit, and Yahtzee was separated from the others, getting caught by a gust of wind and plummeting, crashing through the canopy of the forest below. She was injured, wings torn from the fall, half submerged in the mire, the coolness soothing her aching scales. Perhaps she encountered a particularly advanced host of fungi down in the muck, perhaps she inhaled them, and the mycelium spread through her nervous system. Perhaps Yahtzee was fascinated by the complex and intriguing forms of fungi she'd never seen in her water-bound travels, and dedicated herself to helping them thrive. Whatever the case, Yahtzee never saw her pod again, but based on the accounts of dragons who've come across her by chance, she seems content enough, not appearing distressed or disturbed in any way. She seems to just stick to the damp shadows, often reaching out a talon, tendrils of mycelium stretching towards the observing dragon, such a large colony of various fungi must hunger often, after all, and Yahtzee would appear to share in their resounding goal- to spread, and to consume.