This thing was a Grail that surpassed the Holy Grail in the Moon World's cosmology. It could be said to be one of the earliest wish-granting vessels created by the various gods of the Age of Gods.
However... in the parallel world, Pandora had not opened the box. So once it was opened, what poured out first would inevitably be endless calamity and despair.
Something that could be called despair even in the Age of Gods, after accumulating for several thousand years, had become terrifying enough to overturn the world!
That was just how the Moon World was. Its average combat power might not have been high, but it was exceptionally skilled at playing with concepts. In this world, there were only ultra-high-end combatants and low-to-mid-tier combatants.
They had not come up with many good things, but they had researched plenty of things capable of destroying the world.
Pandora's Box could only be opened by Pandora, who served as its key. Yet over the course of thousands of years, the mechanism that made Pandora the key had already been damaged.
Enzworth's original plan had been to use a Holy Grail to open Pandora's Box, make a wish with the hope inside to save the world, and then use another Holy Grail to close the box.
As it happened, aside from Miyu, the Holy Grail of that parallel world, there was also Illya, a Holy Grail from a Different World.
See? What a coincidence.
Although a massive outpouring of despair might cause widespread human extinction, civilization would not be over as long as a small portion of humanity survived.
From a Magus's perspective, this was the correct choice.
"Munch, munch, you know what? Munch, munch, this red bean paste—black mud—actually tastes pretty good. Munch, munch, it's got some kick!" Chen Luo