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.
As they travel they notice a horrible rotten smell. As they travel it gets stronger and stronger forcing them to cover their noses and mouth less they choke on the horrible smell. Stream full of dead fish. Spawning trout die in mass quantities after they spawn littering areas with dead fish dying and deteriorating in the sun.