Fate/stay night - 2x18 - The Beginning of the Circle- Followmy.tv

Saber defends Shirō from Archer despite her chances of disappearing without a Master to anchor her down to the world, stating that she swore an oath to protect Shirō and that it remains unchanged. However, she is overwhelmed by Archer, forcing Shirō to intervene and take over in the fight. Rin takes advantage of Archer's distraction to form a Master-Servant pact with Saber, which she accepts, therefore making her Rin's new Servant. Fully restored, she subdues Archer, who mocks her for her wish of rectifying her legacy. He then casts Reality Marble, a spell that creates an alternate reality.