What is it about mist or a dense fog that evokes such strong feelings of fear and wonder?
Is it the way that mist cloaks the familiar and makes it unfamiliar? Anyone who has driven in a dense fog will know that fear when it’s difficult to judge distances and you can never be sure when someone will drive out of the fog towards you, even when you’ve driven the same road a thousand times.
Or is it the silence? When every sound is dampened by the footprint of billions of tiny floating droplets and you feel as if no one and nothing could be anywhere near you. And then, the sudden shock of a sound nearby wakes you to the realisation that you were never really alone.
Is it the way sunlight is muted? Frosted by mist the sun appears to be sapped of its strength, coated in a glassy residue, until the mist burns away and you are left dazzled by its brilliance.
Or could it be the filigree of droplets on everything it touches? Tiny drops of water glisten like strands of jewels on every spiderweb and trickle gently from the tender petals of spring flowers.
Or how trees are silhouetted in the winter? Dark branches emerge above the cloud of white like the hands of a drowning man reaching out of the sea.
Maybe it is the way fog rises from the damp earth in the evening. Cold and white it begins to rise like a ghostly sheet, with no obvious point of origin. It builds and glides across the landscape, caressing every blade of grass with a fingertip of ice.
Or is it because anything could jump out at you. It shields the world around you in its white cloak. You put down your guard and believe it to be a real barrier rather than one that is ephemeral. Then from out of the mist a crow flies within inches of your face and swiftly disappears into the fog once again. You didn’t see it coming and it definitely did not see you.
Mist and fog are an elusive and rather otherworldly natural phenomenon, and you can see how easily it evokes a mood of restlessness and anxiety. It can find a home very comfortably in your fantasy writing for that reason. There is no reason why it cannot be as menacing or magical as you need it to be to evoke that natural sense of wonder and fear in your readers.