Cunaida kiseki (S04E12)

With Shirou down, Illya and the others are completely cornered by the infinite horde of Heroic Spirits pouring out of Julian's dark cube. All seems lost when a mysterious sword appears before them! Seizing the new sword, Illya finally puts a stop to the spill, but Julian and Erica escape. Finally able to relax, everyone, including the abandoned Angelica proceeds to Shirou's home to recoup, where they see a whole new side of Miyu. (Crunchyroll)