Chill-barb poison

Chill-barb poison is a dark viscous liquid that through a comparatively simple alchemical process can be bonded with metals creating weapons that stay poisoned for long periods of time. The substance is created from the juice of a plant commonly known as Chill-barb.
Naturally found in the Underdark the frigus tactis passibus (commonly known as Chill-barb) is a small aquatic plant that prefers dark and cool places enveloping whole water-beds with its dark thorny leaves. It is naturally poisonous and believed to have originated from the Elemental plane of frost.
The first to notice its poisonous quality were Orogs who begun first to smother their weapons in this plant's juice, but that was not yet the poison adventurers have the misfortune of facing today. The modern iteration was developed by a conniving drow alchemist who managed to refine the juices in a safe manner producing the popular and practical poison.
The poison was truly perfected by a Duegar transmitter who managed to bind the substance with metals.

Utility

The poison is peculiar in the fact that it does not have an effect if it is imbibed by most Underdark creatures.
So it is mostly used on blades relying on being delivered directly into the bloodstream. After its refinement, the most common use is for hunters or slavers who make use of the poison's slowing qualities to facilitate the capture of elusive prey.

Manufacturing

The technology to produce this poison is laughably simple. The leaves of the plant are squashed to extract the juices that are later reduced and the heavier liquids are bottled and placed in cold storage after which the poison is either applied to a blade or merged with a weapon through the use of specific transmutation spells.

Access & Availability

In the Underdark, a dose of this poison costs a petty sum as it is very easy to produce. Many holds of Duergar go to war armed entirely with Chill-barb weapons.