Oil of Etherealness

Oil of Etherealness is a potion that, when applied to a creature, grants the effect of the Etherealness spell.

Appearance
The oil of etherealness Vox Machina found appeared gray, cloudy, and viscous, and seemed to evaporate at times even while it was within its container. It smelled slightly metallic.

Properties
One vial of oil of etherealness typically contains enough to cover one medium or smaller creature, which takes ten minutes of application. A creature to whom oil of etherealness has been thoroughly applied falls under the effect of the Etherealness spell: it transports them to the Border Ethereal, where the Ethereal Plane and their current plane overlap, for one hour, during which they can see the plane from which they came but can only interact with the Ethereal Plane.

History
Vox Machina found a bottle of oil of etherealness in Umbrasyl's horde. It passed into Vax'ildan's ownership, and he suggested using it when the party was tracking down Raishan, as it would have allowed someone to pass through solid walls, but ultimately chose to save it. He did the same for Mentiri when Vox Machina was in the Nine Hells.

It was ultimately used by Vex'ahlia to locate the Sword of Kas on the Ethereal Plane so that Keyleth could then retrieve it from the corresponding location on the Material Plane.