D&D 5.5e Monster Manual
Poison
Varies
Creatures whos wounds are exposed to this venom by a creature, object, or weapon must succeed on a DC 11 Constitution Saving Throw or take 2d6 poison damage. On a successful save the effected creature takes half the damage.
Warlocks that have been contracted with devils often receive an imp "companion" as part of their pact. Most all milked Imp Venom originates from cases such as this, which undoubtfully, has raised many an eye brow when Imp Venom is sold to an alchemist or Toxicologist.
Cost: 100 gp
Weight: .1 lbs.