The first half of this episode is about Irisviel (Illya’s mom) sneaking into Illya’s school with the help of Rin and Luvia. It’s all good and we get some funny scenes, but this first half doesn’t actually do much to the story progress.
The real deal starts from the second half. A very powerful magician named Bazett comes into Luvia’s house, claiming that she received order to retrieve all the cards. Luvia refuses and a fierce battle starts, destroying the house.
No one from the outside knows what happened inside the house, thanks to a very powerful barrier that contains everything. Rin arrives to the home, but can’t do much to help Luvia, so she chooses to stay hiding. Meanwhile, Miyu is still out there, trying to buy something for Luvia. Finally, when the entire house blows up, Illya and Chloe come to check things out.