“ Magical forests are never a good place to sleep, especially seeing as much of the population is nocturnal. Firewood taken from the wrong tree can turn against its collectors, and a strangling onslaught of angry twigs and branches can be surprisingly severe and difficult to disentangle yourself from. Fires themselves attract enemies, and not only malevolent predators. Giant moths and gloomwings are tempted by the heat and light, but are often misunderstood.”
“ During a storm the PCs come upon a little boy that plays in the rain. Upon further inspection they discover that he has one eye and a long tongue lolling in its mouth. Spit dripping. It is a demon from beyond that can access our realm during storms, it eats all heads that are not its own, living and dead.”
“ A small, primitive village has yet to discover fire, which is a good thing because there are highly flammable (but not otherwise dangerous) gasses in the air. The heroes, blissful in their ignorance, don't know that and think it a wonderful idea to show the locals open flame.”