Ice Fairy Staff

 is a Hardmode summon weapon obtained by giving Frost Core to Genoshi the Keeper. It summons an ice fairy minion to attack enemies with accurate ice bolt shots. Like other minions, the summoned ice fairy is invincible and follows the player for an unlimited amount of time, unless the player dies, summons a replacement minion, or cancels the buff.

Trivia

 * Its name, buff's tooltip, and minion appearance are a reference to Cirno, a character from Touhou Project.