A rapidly approaching figure clad in a black frock appeared within the scattering fragments of the six Black Keys. Kiritsugu couldn’t help but gasp in surprise.

“Time Alter: Double Accel!”

His body reacted whilst his brain reeled from the shock. Kiritsugu cast his spell.

Kiritsugu jumped backward at the last moment. Kirei’s right foot swept ferociously past the tip of Kiritsugu’s nose, and the left foot that followed up the attack didn’t crush Kiritsugu’s throat either. Kirei’s smooth roundhouse kicki completely missed its target, thanks to the confusion caused by Kiritsugu’s double-speed movement.

That had not been within the scope of Kiritsugu's predictions. The Origin round fired from his Contender gun had been nullified – Kiritsugu couldn’t figure out the reason. Even Kirei himself wouldn’t have imagined that the uniqueness of his magecraft had nullified Kiritsugu’s killing blow.

Kirei had never been an orthodox magus. He, whose Magic Circuits had yet to be developed properly, had only obtained a source of prana through utilizing the spare Command Seals he received from Risei. The disposable, single-use Command Seals were all that saved Kirei. The moment the Origin round made contact, the Command Seal that served as his source of prana simply disappeared from Kirei’s arm.

- Fate/Zero: Act 16, Part 6