The shadow-spade winds

This is a permeant swirling storm of a dark mist that slowly travels across the lands of the twilight grove. It is about 300 ft in radius with no discernable eye in the storm, a measurement known through considerable calculations and estimations. No one knows exactly what happens within the storm itself other that there are harsh winds and that it leaves a scarred land behind as it sweeps around the twilight ring. Due to the nature of the twilight groves the plant life seems to quickly come back within a few hours of the storm leaving the area.
While there is still much to be learned about the storm there are some byproducts of the strange storms appearance. One such thing is the shadow-spade rocks, the rocks of which the storm is named after and the only known way to get it. There is also the spade-run, a strange pale thick gel like substance that is very harmful to the bodies of any life, causing intense burning sensations by the faintest of touches.
There is also the subject of why the storm exists in the first place. While studies in the investigation have led to mostly inconclusive results there are a few theories. Two of which go back to the death of Arcadia and splitting of the world into day and night. By the will of the goddess Aroura and the god Helios by will of creating the harsh twilight grove as a natural border between the two sides it created the shadow-spade winds to add to that quest. The other could be that such an extreme difference of temperatures between the two sides and the nature of the difference has caused the magic of the deities that soaks the land to be drawn by the incredible pressure differences to create the storm itself. However much of this part is just speculation.
The storm is a monster to behold up close even on the outside of the mists, with winds ranging from thirty to fifty miles per hour. Shadow-spade and Spade-run being flung off at high velocities, the cries of animals and people being silenced as they cross into the black mist. It doesn't travel fast either, travelling around one mile per hour at best as it slowly inches across the lands.

Manifestation

It looks like a giant cylindrical wall of black mist or clouds slowly drifting through the land. The walls slowly rotate around themselves keeping a strangely perfectly smooth shape to the appearance, as if inside a giant cylindrical glass container. When inside of the Shadow-spade winds all sound and vision are completely gone and it smells of rot and decay from the inside. The winds will whip at you at around 30 to 50 miles per hour in or around the storm.

Localization

This is an occurrences that has only been documented in the twilight ring of the world or better known as the twilight groves.

Type

Metaphysical, Supernatural