“ An insignficant little species, the candlebug (or waxmoth) is a persistent bane for mages and merchants alike. Each the size of a small digit, these little scarabs thrive on wax and burrow up inside candles, ruining them. Sometimes a late-night worker will hear a crack and a sizzle as his candle expires, only to find the half-burned remains of a waxmoth squirming around on his desk. This is very annoying in worlds where candles are expensive...”
“ 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...”
“ Magic is the lifeforce of all living creatures, and it is from it that all life is made - in areas with lots of undead, magic might actually be missing or weak, which puts a whole new spin on how dangerous the undead are. Even simple zombies can be troublesome if you're relying on mages and you hit a pocket of undead making a low-magic zone...”