Abyssal Whistle

The Abyssal Whistle is a Pre-Hardmode Pet summoning item that has a chance to be dropped by any enemy in The Underworld. It spawns an Abyssal Bunny to follow you around. The Abyssal Bunny is immune to damage from enemies and despawns upon player death.

Trivia

 * The Abyssal Whistle and Abyssal Bunny are references to the series Made in Abyss. The Whistle is similar in appearance to the white whistles worn by top-ranking Delvers of the same name, while the Abyssal Bunny resembles a meinastilim.