The Assassin (アサシン, Asashin?) Class Card of the Fifth Ainsworth Holy Grail War was one of eight Class Cards transported to Illya's world in Fate/kaleid liner PRISMA☆ILLYA. Due to the fluctuation in the Assassin that is summoned, the Assassin of the card changed upon transferring over from Miyu's World to Illya's World. The version used by Shinji Matou is different. When later utilized by Miyu Edelfelt, the Assassin of the card changes again.
Upon manifesting, the bodies of the The Hundred-Faced Hassan are similar to their normal appearance, but feature cracked masks with single eyes.
The Assassin Class Card is found in the Fuyuki Forest. The Assassins quickly overwhelm Illya, Miyu Edelfelt, Rin Tohsaka, and Luviagelita Edelfelt. Illya is poisoned, and at the brink of death, she unknowningly released her mana in a massive explosion that manages to defeat the Assassin Class Card while also putting her compainions in danger.
The manifested card reproduces the Zabaniya: Delusional Illusion Noble Phantasm, manifesting numerous individual who throw dirks at the opponent. Compared to normal, the maximum number is greatly decreased.
Including the Assassin Class Card allows for the Mystic Code, Magical Ruby in the case of Illyasviel von Einzbern, to become a decoy the exact image of the user. The user will be concealed for a few seconds, but will be revealed after the decoy is destroyed. Although the decoy takes damage, the item used to transform remain intact after returning to its normal form.
Installing the Assassin Class Card gives the user a version of Assassin's garb, grants use of their daggers, and transforms the Kaleidostick into one of Assassin's skull masks. Once clad like this, the user can still make use of the duplicates with Zabaniya, but also gains the ability of Assassin's Presence Concealment.
« A person well-versed retorted with "hey, isn't this the 4th one?" at the numerous excuses I had the pleasure of making up, yup, that's why. I want to see the Illya who pulls out opponent's hearts with her right hand as well. »
- Fate/kaleid liner PRISMA☆ILLYA - Chapter 10: "Violence and Desertion"
- Fate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 20: "To the Princess"