Oona

An unfortunate parasite that infects weakened dragons, the Cordysepis Affliction starts in patches and can grow to infect large swathes of skin and scales. It may be spread through ingestion of spores released during an infected's blooming period, or by close contact during any other time of the cycle. The average Cordysepsis goes through the basic cycle of infection and incubation, growth, spore release and die off. Depending on the specific fungus that has infected the dragon, they may develop an immunity to further infections, remain infected for life, or even expire when the fungus has completed its life cycle. If caught in its early stages, there is a slim chance the fungus may be removed through various methods such as outside magic and sulfur baths. Without immediate detection and treatment, however, the cordysepsis becomes ingrained within its victim.
The natural variation among strains can make treatment difficult. Many strains can return after a full flowering and some are know to flower multiple times a year. No breed is safe from infection, and hatchlings commonly catch it at birth from their infested parents. The parasitic fungus tends to grow slower on younger dragons, as they are less mobile. Once they are fully flighted or mobile, it will grow much more vigorously. Some advanced specimens appear to have degraded mentally, becoming drones serving the needs of the fungus. Stronger dragons hold out, their powerful immune systems able to fend off the infestation enough to retain their mental faculties. That doesn't prevent them from seeking high places when their infection is in full bloom, helping to spread the spores from their dusty, flaking flesh. For few among the ranks of Cordysepsis, it is a point of pride to retain one's individuality while in the throes of infection.