The Black Plague (And other diseases) design help

[Fako]

Are you sure about those short incubation times and the high CON damage on the second version?

I would think that a longish period of contagiousness before symptoms appear would be necessary for a disease to become a plague. Also, 3d4 will kill the average NPC on the second failed save on average. Was it really THAT fast of a progression of the disease?

The pneumonic plague is known for being incredibly fast and lethal. From the Center for Disease Control's website on the disease, found here:

With pneumonic plague, the first signs of illness are fever, headache, weakness, and rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery sputum. The pneumonia progresses for 2 to 4 days and may cause respiratory failure and shock. Without early treatment, patients may die.

From wikipedia's article, found here:

It could kill 90%–100% of a population if the victims coughed and passed on the bacteria.
-snip-
Without treatment, the mortality rate from pneumonic plague approaches 100%.

However, from what I can tell, it could take up to a week before symptoms began to show, so the incubation period should probably be 1d6 days...

As for how to make the players afraid of disease, I'd recommend introducing magically enhanced strains that progress more rapidly than the normal versions, requiring a save once every hour, minute, or even round, depending on your preferred flavor. Few things are scarier (disease-wise) than watching a commoner try to help someone, only to die of the disease in under a minute...