Use stream of consciousness to answer the following. At the end of the second season, Willow begins to study magic following the murder of the computer teacher and spell caster Jenny Calendar (Robia LaMorte). Willow is able to perform a complicated spell to restore the soul of Angel, a vampire who is also Calendar's murderer and Buffy's boyfriend. During the third season three episodes explore Willow's backstory and foreshadow her development. In "Gingerbread", her home life is made clearer: Sunnydale falls under the spell of a demon who throws the town's adults into a moral panic, and Willow's mother is portrayed as a career-obsessed academic who is unable to communicate with her daughter, eventually trying to burn Willow at the stake for being involved in witchcraft; her father is never featured. In "The Wish" a vengeance demon named Anya (Emma Caulfield) grants Cordelia's wish that Buffy never came to Sunnydale, showing what would happen if it were overrun with vampires. In this alternate reality, Willow is an aggressively bisexual vampire. In a related episode, "Doppelgangland", Willow meets "Vamp Willow", who dresses provocatively and flirts with her.

When does willow become a witch in buffy the vampire slayer?
To answer the question, consider the following: At the end of the second season, Willow begins to study magic following the murder of the computer teacher and spell caster Jenny Calendar (Robia LaMorte). Final answer: At the end of the second season.