At this exact moment, boom! An ear splitting explosion reverberated into Waver’s ears.

No, to be specific, it was not a sound, but a hearing stimulus. It directly attacked Waver’s sensitive nerves of a magus - in other words, a magecraft impulse.

“What was that? ......At the east.”

As a Servant Alexander could also felt the stimulus clearly.

From the open curtains, one could see a layer of cloud dispersing in the clear sky. Although the pattern of the cloud looked like those clouds formed by fireworks, the twinkling glow did not look like normal fireworks smoke at all.

Despite the fact that Waver could see the smoke clearly, because it was formed due to magecraft, people besides magi could not see it. The same goes to the noise. To a normal person, it was but a sound of normal fireworks.

“That position…is where Fuyuki church is, right?”

- Fate/Zero: Act 5, Part 4