Creating a disease

How have you guys handled diseases. I want to plan an encounter with rats that have a disease. In pathfinder and other such games it would usually give minuses to stats. But with open legend that seems like not as good of an idea.
Thanks in advance for any ideas.

Sickened or Fatigue are the banes which best capture the feeling of a generic illness. Slowly increasing lethal damage also works, as they are weakened and unable to withstand as much fighting before collapsing or giving up.

For really interesting diseases though (maybe a bit too much effort to put into an encounter with rats, but up to you) the disease should have a theme and a progression. There was a game I ran in a different system, where water was scarce but people kept catching “water sickness” that progressed roughly as follows when translated in to OL:

At the start of each day after being exposed, roll Fortitude. On a 15+ you are fighting off the sickness, drop 1 level. On a 10-15, no change. If you roll less than 10, the sickness advances 1 step.

  1. No sign of infection
  2. Drooling, nose running, eyes watering - disadvantage to social rolls
  3. Coughing up water - disadvantage to all rolls
  4. Hallucinations - disadvantage to all rolls, but advantage to Prescience rolls
  5. Drowning - immediate help needed, or the character dies