Dust Invisible

Description:
A fine dust of various unknown ingredients, the grains have the colors of grey, black, silver, brown, and others. The dusts itself is not harmful. It is not very common on the market, the durable variant can fetch a high price.

Magical Properties:
When thrown, the dust disperses gently and clings to all surfaces, including those 'not entirely here'. It allows to see the shapes of invisible and even immaterial beings, but ignores illusions, so some may be recognized as such. It is useful for fighting ghostly creatures, though they can get rid of this mark by passing through a wall.

Creation and History:
The original Dust Of Sight was created by the priests of a vanished sect, developed to tear away the veil that hides the ultimate truth. Whether they found their truth, or something else, they are no more.

The creation itself was a potent ritual. Four virgins would recite holy texts for days, sacred incense was burned, and prayers uttered... all that is gone. What remains is a dirty and easy alchemistic process. The basic formula can be found in many resources:

Ashes of Dead,
Grain Despoiled.
Love Letter Burned,
Curse Employed.

Stirring thryce Westward, your Blood won't be Spared,
Cooling the Night through, on the Headman's Blade.

Use it in Haste, lest it sees thryce paired Days,
Pain you will feel, for an Old Ones Disgrace.

Oh, right: the formula is well known, but there are many possible interpretations (for a start, the "Ashes of Dead" can mean the ashes gained by the burning of the dead, or the ashes that stay behind after undead burned by sunlight, etc), not to speak of the manufacture. How widespread is the secret will determine the price of Dust.

Sometimes, remains of the original Dust of Sight are found, fully effective after hundreds of years; what is produced now lasts a few days. After the expiration period, or in case of partial success may manifest side effects. 'The veil that hides the truth' may be pierced even more; going as far as revealing what lies beneath the skins of people... not a sight for the faint of heart.