Void Residue

A substance created as a rare byproduct of conjuration magics, it's considered to be the result of dimensions weakening. Something like a small crack in reality which displays contradictory physical traits and can only be seen as a grey static. Typically it manifests as a powdery feeling sludgy liquid that holds itself together when pulled to stay one solid mass, though other forms have been rarely seen. Each 'dose' of the substance is one of these self contained masses, usually no more than a vial's worth.

There is no known way to reliably create void residue and due to the rarity it is not normally found for sale. Even when trying to sell only rare powerful casters with a need for teleportaion, something surprisingly rare in itself, would bother buying it. However every casting of a conjuration spell higher than spell level 3 has a 1% chance to create a dose at the origin of the spell or at the end location if a teleport/summoning spell.