“ A demon in human shape that murders travellers, however, he can only travel a certain distance from his home.One the adventures have passed that point, he is no threat to them.”
“ Golden coins that turn to lead within a few hours of being taken from their place of origin, causing a lot of trouble for whoever spends them.”
“ 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...”