The Afflictionist: A Dungeon World Playbook (2014)

From publisher blurb:

There are more dangers in Dungeon World than just in the dungeons alone. In the deep forgotten recesses of the cities; disease runs rampant killing men, women, and children alike. Treatment is all but impossible to come by, as those who try to assist only spread the infection further. That’s where you come in.

You, who are basically immune to disease, poison, and venom; your touch can draw illness from the stricken. You are a boon to the ever expanding communities throughout Dungeon World.

You dare not keep all those toxins inside you though. You also have to ability to let loose those plagues upon others, which makes you an asset to the adventuring parties as well.

So go forth you merchant of pox, spread your name as you spread your pestilence.