Foglets - The Witcher 3

If night ever catches you in the swamps, stay put and wait for dawn, even if it means standing waist-deep in water with leeches crawling down your trousers. Most important of all, if you see a light in the fog, never, and I mean never, go towards it.
– Johannes Strudd, guide

Fog is the traveler's foe. In the forest, it can make one lose one's way , at sea, it can send one sailing into the rocks. Yet such dangers are nothing compared to the monsters known as foglets which sometimes lurk within it. These creatures have powerful arms and claws like Zerrikanian kinjals, yet what makes them truly dangerous is their mastery of deception, beguilement and disorientation. Many times they need not attack at all, instead simply driving their prey to madness or into boggy marshlands, after which they wait patiently for it to drown in the muddy waters.

Foglets may appear wherever thick fog can arise: swamplands, mountain passes or the shores of rivers and lakes. If no fog is forthcoming, they create or summon it themselves. Quickly thickening air undisturbed by the wind infallibly signals a foglet is present - and preparing an attack.

Thick clouds of mist not only allow foglets to remain unseen, but also serve as their weapons. By manipulating fog they can separate travelers from each other, hide trails and deafen noise. Like ghastly glowworms, their bodies emit a pale light they use to lure those lost in the fog towards the ravines, swamps or caves in which they make their lairs.

Even if a traveler spies his pursuer and manages to attack, the foglet can disappear into thin air before the blade hits its target. Some foglets are additionally said to possess an ability to create complicated illusions rivaling that of human mages. Whether that is true or merely one of the dark legends men tell about these mysterious monsters remains uncertain.

When fighting foglets, a witcher must remain calm and keep his wits about him no matter what. Since foglets can take on immaterial form, a slight shimmer of air or a rustle in the grass might be the only clues a witcher has to their location. Casting the Aard Sign at these beings will cause them to become tangible, giving purchase to blades and other weapons.