Imp

Imps are lesser devils found in the Nine Hells and in the Elemental Plane of Fire, but occasionally residing peaceably among mortals on Exandria.

Description
Imps differ somewhat in appearance—some are dark, ashen-grey with yellow eyes, others red—but they are generally described as looking like tiny, leathery-skinned, winged humanoids with barbed tails and sharp teeth. They are capable of turning invisible, and their tails have potent poison stingers. Some have been seen wearing armor.

Campaign 1: Vox Machina

 * When Vox Machina investigated the home of Sir Gregory Fince, they found him slain in the basement, and encountered an imp in the upstairs library.
 * After Thordak escaped from the Elemental Plane of Fire and razed Pyrah, imps were among the creatures wandering through the widened, unguarded rift into the Sunderpeak Mountains. Vox Machina didn't encounter any by the time they returned to the Cindergrove.
 * Vasa worked for Ipkesh in the City of Dis.
 * Also in Dis, Vox Machina attacked two imps who had been invisibly helping Utugash operate the traps in his throne chamber.
 * The messenger Senokir sends across the planes to Vox Machina is an imp.
 * Demistrik was an imp living with Sprigg. When that house was destroyed, he quickly made his way to another home in Kraghammer.

Campaign 2: The Mighty Nein

 * The Mighty Nein encountered three imps while fighting Kylre.
 * Two imps reside in Ava Endlewood's shop in Uthodurn. Reani knows about them, but Samliel hasn't told her to kill them.
 * Fjord inadvertently discovered an imp in Vess DeRogna's tower.

One-shots

 * In the Battle Royale, an imp ate the gem that changed Percy to Mollymauk and back.
 * In the, imps helped with the production of the televised battle. One was named Lestat.
 * In the, searching for cultist Madrak, Lucky Jack, Yasha, Beau, and Nott encountered Bozyn, the imp who guided the group directly to them.

Abilities
Much of the following is taken from the Monster Manual, 5th Edition, p. 76, but some traits are demonstrated onstream and timestamped.

Immunities:
 * Damage Resistance: Cold, bludgeoning/piercing/slashing from nonmagical weapons that aren't silvered.
 * Damage Immunities: Fire and poison.
 * Condition Immunities: Poisoned.

Abilities:
 * Shapechancher: The imp can polymorph into a beast form that resembles a rat, a raven, or a spider, or back into its true form.
 * Devil Sight: Magical darkness doesn't impede the imp's darkvision.
 * Magic Resistance: The imp has advantage on saving throws against spells and other magical effects.
 * Invisibility: The imp can magically turn invisible.

Attacks:
 * Sting: The imp can attack with it stinger, which can poison its target.