Jack materialized her body. She was gripping an antique lantern in her hand.

"What is that?"

"This is our Bounded Field Noble Phantasm: 'The Mist'."

Servants are heroes from ancient times, and their tales revolve around certain weapons and tools, big and small.

-- A holy sword of light, forged in the planet.

-- A demonic spear which pierces the heart without exception through the reversal of causality.

-- Reins which control beasts from the Age of Gods.

The lantern Jack holds is one of these.

"Have you ever heard of 'the Smoke', Mother?"

"I have. That means London, doesn't it?"

"Yes. When we were there, the smog in London was horrible. It was pitch black -- so bad that we couldn't breathe, so bad we couldn't open our eyes."

The mixture of smoke and fog released during the burning of coal is called smog.

From the 19th to the 20th century, London had been harassed by smog countless times.

The worst of all was the Great Smog of 1952. It was said that the thick mist of sulfur covering London caused over 10,000 deaths.

Jack opened the shutter of the lantern, and gently touched the candle inside.

A flame was lit and at the same time, something like smoke began to leak out from the bottom of the lantern.

"This Noble Phantasm can recreate that mist.

No one can ever escape it. They'll die in agony, all of them."

- Fate/Apocrypha: Unbirth