Call me "Creature", lostling, half-dragon of the planes; ie Corporal John Hearthfeld, Esq. - Assassin/ Enforcer "Rat-snake" .
Starts with scene excerpts, followed by working notes, ends with actual used Character Sheet data.
Pick up a pathology/microbiology book, and add the diseases/syndroms to your game. Your players will freak out.
Coughed at? Diphteria. or tuberculosis?
Drunk from a muddy stream? Or just walked through? Well, let us introduce you to schistosomiasis...
Hit by a stream of energy? Too moch mana is ust like too much radioactivity - perhaps all mages could develop cancer early if too powerful...