|This is an Enemy-only Servant. It cannot be obtained as a playable-Servant through any means.|
|Japanese Name: テスタメント|
|AKA: Dark Illya|
|ID: Null||Cost: 16|
|Voice Actor: Kadowaki Mai||Illustrator: Hiroyama Hiroshi|
|Attribute: Man||Growth Curve: Reverse S|
|Traits: Servant, Humanoid, Female, Weak to Enuma Elish|
|3 | 5 | 1 | 5|
|Active Skills||Passive Skills||Noble Phantasm||Ascension||Skill Upgrade||Bond Level||Biography||Trivia|
- Testament is the antagonist of the Prisma Causeway Event. She is an NPC and enemy version of Illyasviel von Einzbern. She is currently unobtainable.
- Similar in-game to Illyasviel von Einzbern, she has several differences to her playable counterpart, such as having different skills, different Noble Phantasm name and a more corrupted look.
- Testament's servant art card looks like Illya from Prisma Cosmos CE.