Movie
Description
In the film Fate/kaleid liner Prisma Illya: Vow in the Snow, the Assassin Card User is not a separate character but rather a form assumed by the protagonist, Miyu Edelfelt. She gains this power by utilising one of the seven Class Cards, mystical artifacts that contain the essence of legendary heroic spirits. In this specific instance, the card summons the spirit of Hassan of Serenity, one of the nineteen leaders of the historical Order of Assassins who each carry the name Hassan-i-Sabbah.

The personality and motivations of the user are defined by the desperate circumstances of the story, which serves as a prequel to the main events of Fate/kaleid liner Prisma Illya 3rei. Miyu is not a typical magical girl but a "Holy Grail," a living vessel of immense power who was taken from her original world and adopted into the Ainsworth family. The film depicts her struggle against her adoptive brother, Julian Ainsworth, who seeks to use her for his own ritual. When Miyu accesses the Assassin Card, her own quiet, reserved, and protective nature remains dominant, but it is sharpened into a lethal, cold, and efficient resolve. Her primary motivation is survival and escape, as she fights not for justice or glory, but to break free from the Ainsworths and find her real brother, Shirou Emiya.

In the role of the story, the Assassin Card is one of several cards Miyu is forced to use in a gauntlet of battles orchestrated by Julian to test her worthiness as a vessel. The battle with the Assassin Card is a pivotal moment showcasing her tactical ingenuity and the stark, violent reality of her existence. Unlike the brightly coloured magical girl battles of the parent series, this confrontation is shadowy and deadly, reflecting the nature of the card itself.

Key relationships are defined by this struggle. Her primary antagonist is Julian Ainsworth, who views her as a tool to save the world, creating a deeply personal conflict. She also fights against Angelica Ainsworth, another powerful card user, and the battle involving the Assassin Card is part of her wider attempt to overcome the Ainsworth family's forces. Her entire character arc is oriented towards reuniting with Shirou, and her development is one of increasing desperation and weariness. As she uses more cards, including Assassin, the immense physical and magical toll becomes evident, showing her transformation from a hopeful child into a tragic figure willing to sacrifice her own body for a single chance at freedom.

The notable abilities granted by the Assassin Card are fundamentally different from a standard magical girl transformation. Upon Installing the card, Miyu merges with the spirit of Hassan of Serenity, granting her the physical characteristics and weaponry of the legendary poisoner. Her primary weapons become a set of white, kunai-shaped dirks, which she can use for both slashing melee attacks and as thrown projectiles. The signature ability of this form, however, is Zabaniya: Delusional Poison Body. This passive Noble Phantasm transforms every part of her body into a lethal toxin. Her skin, fingernails, breath, and even the droplets of her sweat become virulent poisons capable of robbing an opponent of their freedom of movement and control over their body with just a light touch or by being carried on the wind. This makes the Assassin form exceptionally dangerous in close quarters, requiring a fighting style of swift, precise, and minimal-contact strikes, as even a single scratch is enough to end a battle.