the Great Contagion

The Great Contagion is a plague that struck Creation at the end of the Shogunate Era. The plague has no cure and kills nine lives out of ten, man and cattle alike. 

The origin of the plague is officially unknown. However, the keeper of secrets know this dicease to have originated from the Underworld.

In RY 831, a similar version of this plague reoccured in the city of Valor after the curse upon seven bloodlines of the city by Lewo Ungurr. Though the persistance of Broken Mask of Forsaken Truth and his Deathknight brothers, the population of this city could be saved. 
This new similar version of the plague is currently ravaging the Kingdom of Jaden.