Green Field Cutting Through the Thousand Mountains.
One of the twin swords possessed by the war god that appears in Mesopotamian mythology, Zababa… It is said to be so, but it is not sure if this is “the real thing,” or just “a different thing” that Gilgamesh calls that. Ig-Alima and Sul-sagana are the names of the children of the god, and there is the possibility that Gilgamesh named it like that as a nickname, same as with the Sword of Rapture, Ea.
Alias: Cleaving Mountain Sword. A long and unrefined gigantic sword that can cut even through a thousand mountains.

It cuts not with a blade alone.
It breaks up not with mass alone.
This sword made by a god comprehends the concept of “skyline.”
That is the very same principle through which heaven and earth are absolutely separated, and as a result of the principle itself leaking out into the brandishing of the sword, this gigantic sword easily severs a thousand mountains.

Originally only an equal Divine Construct could confront it, to say nothing about how it is conversely impossible to break that sword blade.
That a magical girl could accomplish that once is astonishing, but — it stands to reason.
Because the star the girl wished upon shines preciously even in the crepuscule of despair that makes heaven and earth prominent, and overshadows the endless field with its light.

PRISMA material/petit: Encyclopedia of Prisma Illya MOVIE