Quasit

Quasits are tiny, sneaky demons who rank very low among fiends and are sometimes used as familiars.

Appearance
The quasits encountered by the Mighty Nein beneath Asarius were about two feet tall and had leathery, blue-gray skin and wide, black eyes.

Abilities
The following is drawn from the Monster Manual, 5th Edition, but some abilities are demonstrated onstream.
 * Invisibility: As an action, can turn invisible until it attacks, uses its Scare ability, or loses concentration
 * Shapechanger: As an action, can polymorph into a bat, centipede, or toad, or back into its true form
 * Magic Resistance: Advantage on saving throws against spells and magical effects
 * Damage Immunities: Poison
 * Damage Resistances: Cold, fire, lightning, bludgeoning/slashing/piercing from nonmagical weapons
 * Condition Immunities: Poisoned
 * Scare: Can force one nearby creature to make a Wisdom saving throw, becoming frightened for one minute on a failure; subsequent saving throws are made with disadvantage if the quasit is within sight

History
When the Mighty Nein descended into a well to investigate a demonic incursion into Asarius, several of the demons they fought were quasits, one of which Jester chopped up as food for Yarnball, her moorbounder.

In the low-level adventure Poached Eggs in the Tal'Dorei Campaign Setting sourcebook, a quasit named Wapalmter leads a group of human poachers.

Trivia

 * In the Explorer's Guide to Wildemount, one of the "fateful moments" a player can roll for their character's heroic chronicle is a dream of a demon lord, after which the character can ritually summon a quasit as a familiar.