The space in the underground District 22 was a giant cylindrical area, and the entrance looked like it was outside this 2 kilometer diameter area , continuing to spiral down to the bottom

[...]

Acqua jumped 20m up into the air-- no, he broke through the volcanic crater-like opening that connected the 4th and 5th levels, jumping up at least twice the height of the previous one.

[...]

A while back, that meteor-like destructive power had slammed onto the Earth and defeated Kanzaki in one hit, and even if Kanzaki was at her best condition, she wouldn't be able to endure it. Besides, the jump this time was twice the height of the previous one, and the entire Amakusa definitely wouldn't be able to take this hit. The entire 5th level may end up getting destroyed.

"Sometimes, depicting this power called the Truth of God, LET YOUR MERCY RISE TO THE HEAVENS!!"

A huge velocity, and a falling Acqua. The mace that was basking in moonlight dragged a bluish-white tail behind it.

(Is it over!?)

The defensive array was formed by numerous steel wires, and Kanzaki herself wanted to protect that pile of metal through magic. But this wasn't enough, this one hit from Acqua mercilessly aimed at the floor.

Having taken one hit from it, Kanzaki knew that if she took another of that hit, she would definitely die. And not only Kanzaki, it was likely that even the Amakusa members around her would be dead.

Toaru Majutsu no Index vol.16 ch.1 pt.7, ch.4 pt.4