Spore Sickness
Warning: This disease is very impactful to your party and should not be handed out lightly.
Spore Sickness is contracted by ingesting or inhaling powered Mirror Moss, a rare fungus that camouflages itself with a naturally-occurring illusion. It causes creatures to see hallucinations and eventually go mad.
Creatures that ingest or inhale the fungus must succeed on a DC 18 Constitution saving throw or become infected. If infected, the creature is Poisoned for 1 hour with lingering symptoms beginning to appear after 2d4 hours.
Phase 1 - Minor Hallucinations.
The creature begins to see and hear things that aren't there. They have disadvantage on Perception and Insight checks.
Phase 2 - Blurred Reality.
One day after the creature is infected or after they take their next long rest, the symptoms grow worse. The hallucinations become more persistent and the creature begins to question what's real and what's fake. They are plagued with nightmares, and the line between dreaming and the waking world begins to blur. The creature must make a Constitution saving throw whenever they finish a long rest, with a DC equal to 12 plus the number of previous failures they have made on this check. On a failure, the creature only gains the benefits of a short rest, not a long one.
Phase 3 - Madness.
After three failed saving throws, the symptoms become overwhelming. The creature experiences the world as a chaotic mix of fact and fiction, unable to make their way in the world. Whenever the creature finishes a long rest, they must roll on the short-term madness table. Whatever effect is chosen lasts until they next finish a long rest. Unless they are cared for, they will likely not survive.
Curing the Disease
Spore Sickness can be cured by the Lesser Restoration spell while it is still in Phase 1, or the Greater Restoration spell once it has progressed to Phase 2. Once it has reached Phase 3, only the Wish spell or other incredibly powerful magic can cure the disease. However, there are other ways that some say can cure the disease at any stage:
From Whence It Came.
Mirror Moss grows on the damp walls of jungle caves, where it hides itself from predators using its illusion magic. There is one creature that is known to thwart these defenses and can live quite happily in these caves, feasting on the normally-invisible Mirror Moss: the Scuttermite. They are rare but a druid may know where to find them, and an extract from their saliva may be able to counteract the sickness. But beware: Scuttermites aren't dangerous, but they are rarely the only creature that dwells in their caves...
Unicorn Tears.
The healing properties found in Unicorn Tears are known to have powerful curative properties. There are few diseases that they cannot purge from a creature, if the victim's heart is pure enough. If not, the consequences could be catastrophic...
Helpful Guardian.
Guardian Nagas are well-versed in all manner of protective and healing magic and may be able to reverse the course of the disease. But they are also loathe to leave their domains, so you will need to bring the infected to them for treatment. Unfortunately, they are rarely in a location that is easily reached...
Cleansing Waters.
There are stories of a magical pool that sits at a convergence between the Fey Realm and the Plane of Water, and submersing a creature in this water is said to cure any disease and heal any wound. The location of the pool has been lost for centuries, but recently there have been rumors that someone is claiming to have seen it...
November 2024
Not all is as it seems.
Be very careful when handling Mirror Moss! It's harmless in its normal state, but once dried and made into a powder it is very dangerous if inhaled. More than one mage have lost their minds attempting to process this powder into a Dust of Seeming to harness its potent magical properties, but ended up afflicted with the deadly Spore Sickness
This work includes material taken from the System Reference Document 5.2 ("SRD 5.2") by Wizards of the Coast LLC and available at https://www.dndbeyond.com/srd. The SRD 5.2 is licensed under the Creative Commons Attribution 4.0 International License available at https://creativecommons.org/licenses/by/4.0/legalcode.