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Intro. Saber Alter Artoria Pendragon is a corrupted version of Artoria Pendragon, King Arthur, who . His personality is crueler and darker, and his sword, Excalibur, transforms into Excalibur Morgan, a corrupted and black version. The corruption occurs when Artoria is absorbed by the black sludge of the Holy Grail, which alters her perspective from being an idealistic hero to one who believes that heroism is being hated by others for your actions. Saber Alter is not a different character, but the same Artoria Pendragon who has been corrupted by the "sludge" of the Holy Grail, an evil residue generated by Angra Mainyu (the "Evil of All Evils"). In short, Saber Alter is the embodiment of the darker and more violent side of King Arthur, manifested through the corrupting influence of the Holy Grail.

Saber Alter (Artoria Pendragon)

@Juan