It was an inexplicable phenomenon caused by a chance occurrence.
A vast island of ice rose in the Arctic, with an iceberg in its very center radiating an unusual sense of holiness.
There was no doubt it was the Holy Grail, yet it was an Ice Grail born of a true miracle.
Water can contain all things. Things with compatible natures can accept one another, while those with incompatible natures will never become one. But when water freezes into ice, everything becomes a single, unique entity. What you see before you is never the whole picture. Perhaps he is deceiving you, perhaps he is hiding something, or perhaps you have simply misunderstood. Never trust the person you see before you, for that image is incomplete. Perhaps he is someone else entirely.
The Servants summoned for this war are ice-bound beings, each frozen into a single, unique entity.
The war for the holy Ice Grail has begun.