When was the last time a character caught a cold or flu? Real people get them every now and again even with solid heating and dry interiors. Your characters are out in the cold and wet, and even inside is not always dry and warm. Imagine having to stop your dungeon crawl, sitting in a tight defensive position, while you all are feverish.
Arkths or Ravagers: These are large landbound crablike creatures about the size of Grizzly Bears. They live partially in the astreal plane. Their food is magic. They can sense it at huge distances. Since spells and such are hard to eat (being in motion) and magical places are the equivalent of a sea of krill to them, they are looking for magic stashed in concrete places. Their primary food source is magic items, alchemical potions, and enchantments. They do a pretty good job of mangling/ eating the physical aspect of said items in the process of chowing down. These things will be the bane of dungeons everywhere, as they will slowly eat away much of the treasure (and the magical traps... so it can be advantagous to follow these things). Note: They will attack people with highly magical natures (i.e. high magic powers). They will probably kill the person in the process of sucking out the power.
Khor are a monsterous and violent race. Within five years of being born, they grow to about half human size and are very, very inteligent. As they get older, they get larger... unfortunately they become less intelligent. After their adolecesence (about seven years), they grow to human size and are of a low human intelligence. As they age, they grow larger, slower, and stupider. Most of them end their lives 3 to 4 meters in height. Khor have been reported upto 10 meters tall, though those elder giant Khor do little but hit anything that disturbs them.
As they age they get larger, they don't seem to ever die of natural causes.
After particularly intense storm, a green glowing fungi can be found on the trees and plants. Also new monsters seem to be in the region. These storm are obviously bringing these things from other places and depositing them with the wind, rain, and goop upon the land.
Also called "pale-yellow witch" by alchemists, this mineral is known to possess a peculiar attribute. When found, a Yupiorite will appear the palest yellow. Rather than crystalline in structure, Yupiorite occurs in weird, smooth, ovaline shapes, as if already carved by skilled hands to serve as ring or necklace ornaments. Yupiorite somehow detects and reacts to mood. When the wearer of the gem is content, calm, and happy, the stone will remain the palest yellow. As the person gets more excited, angry, or otherwise stimulated, the mineral will darken progressively to a dark corn-yellow in color. Why the gem reacts this way to sentient mood swings, is still debated by gemologists and alchemists alike.
It is said that the Elven Halls of Vala-Aluduwy are resplendent with wall-sized mirrors of pure Yupiorite, showing plainly and ironically, the emotions of everyone present, despite the Elven love of restraint and stoicism.
"Cave-grass" or "cave-pine" is a deep forest green in color, rare and often mistaken for other minerals, though otherwise mundane. Crystals form into tiny, ultra-thin, needle-like clusters by the hundreds of thousands, creating vast dark green bursts and structures, resembling evergreen conifers, if viewed by any sort of light. Despite its ephemeral shape, Aragdulose is only second to a diamond in hardness.
Dwarves are said to keep these mineral "trees" in their homes, putting them up during festive family holidays, leaving presents beneath them, for kin to open.