Joan Alter 〈8K〉

She is best used in teams that can provide critical stars to maximize her high critical damage potential. Jeanne d'Arc Alter | TYPE-MOON Wiki | Fandom

Boosts critical damage (+50%) and star gathering rate for 3 turns (ideal to level first). Joan Alter

Born from a wish upon the Holy Grail by Gilles de Rais, she represents a twisted version of Jeanne d'Arc seeking revenge. Over time, she develops into her own person rather than just an imitation of her saintly self. She is best used in teams that can

A party-wide damage boost that doubles for [Dragon] trait allies (level last). Over time, she develops into her own person

Grants a 50% Buster buff for 1 turn (level second).

Based on the search results, "Joan Alter" (often referred to as or Jalter ) is a popular character from the Fate/Grand Order (FGO) mobile game and anime franchise. She is a distorted, "Altered" version of the historical Joan of Arc, appearing as an Avenger-class servant designed to be a vengeful figure.