The black fog that twined about Berserker’s entire body was originally a Noble Phantasm that had the purpose of not only hiding his visage, but also of mimicking any person in order to deceive enemies’ ears and eyes. Ever since Berserker had been stripped of his rationality, this ability could not be brought into play. Kariya had forced this ability to manifest through the power of the Command Spells and made it possible to disguise Berserker as a fake Rider. But this ability could only be used once.

“Ar… ur…”

- Fate/Zero: Act 14, Part 3