Fate/Zero 2nd Season

Synopsis

As Kiritsugu and Kirei engage in an intense duel, Saber shares a last conversation with Berserker before he dies by her hand. As Kiritsugu and Kirei both prepare to deliver the finishing blow to the other, a black ooze pouring from the Grail crashes through the ceiling and covers them. Kiritsugu finds himself in an illusory world where Angra Mainyu, taking the form of Irisviel, tells him he is worthy of using it to make a wish, making Kiritsugu the winner of the war. However, Kiritsugu is shocked to find that the Grail has been corrupted, and watches it deconstruct his belief in killing the few for the sake of the many and being told no one can "save the world" and end conflict without killing off all of humanity. Angra Mainyu attempts to convince Kiritsugu to make his wish by assuming the forms of both Irisviel and Illya and promising he will be together with them again at the cost of everyone else. However, Kiritsugu rejects the Grail, declaring he will not sacrifice the rest of humanity for the sake of his personal happiness, and realizing that the Grail has been corrupted and now seeks only to turn victors' wishes into global genocide. For this, he is cursed by Angra Mainyu, shortening his lifespan. Back outside, Kirei scolds Kiritsugu for refusing the Grail and wasting the wish. Kirei pleads with Kiritsugu to give the wish to him so that he may find the meaning of his existence, but Kiritsugu shoots him. Saber soon arrives at the Grail's stage and encounters Archer, who demands that she surrender and devote herself to him as his wife. Kiritsugu appears in the middle of their exchange and, to the horror of both Servants, uses his two remaining Command Seals to force Saber to destroy the Holy Grail with Excalibur.

(Source: Wikipedia)