Roll 3d6 on the attribute dice map. The low roll indicates how infectious the disease is and where the infection comes from, the high roll indicates how severe it is and what limb/organ is affected, and the middle roll indicates how fast it progresses.
Once exposed, victims start at the severity level of incubation (no symptoms.) Progression indicates how often to make saving throws to drop one level of severity; if the save fails, the victim is still infected, and the GM rolls a d6 for an Avoid Danger roll, with a 6+ indicating that the disease progresses to the next severity. Severity is described in full elsewhere, but the effects are summarized as "nuisance only," "penalty," "double penalty (w/ risk of permanent loss,)" and "death".
Doubles indicate spreading diseases (if low-mid match) or wasting disease (if mid-high match;) triples indicate spreading wasting disease. Spreading diseases require a separate Avoid Danger roll; roll the d6 on the attribute dice map, and on a 6+, that new location is affected. Wasting diseases cause 1 hp damage on every failed roll.
Interpretations of dice map for source of infection:
- Strength: transferred through animal contact
- Dexterity: transferred through plant contact
- Constitution: transferred through bodily fluids
- Intelligence: transferred magically or psychically
- Wisdom: transferred through senses (stress)
- Charisma: transferred through breath
- Hub: transferred through filth, dung, decaying matter
- Strength: arms or upper body
- Dexterity: legs or lower body
- Constitution: vital organs
- Intelligence: confusion or concussion damage
- Wisdom: sensory organs
- Charisma: skin or hair
- Hub: blood or lymph nodes
The explanation of the contagion levels refers to procedures needed to prevent contagion:
- None: The victim's exposure was a fluke. No one else will catch the disease without long-term replication of the original exposure conditions.
- Simple: Any exposure risks infection, but any reasonable steps automatically prevent infection. No roll needed.
- Difficult: Those attempting to avoid infection can still be infected if they fail an Avoid Accident roll (more than 4 on d6;) extreme measures lower the difficulty.
- Extreme: Only extreme measures have a chance of preventing infection; these may be beyond the technical ability of the characters.