By Othinus’s reckoning, Vishnu Avatara had manifested for less than ten seconds.

Dáinsleif was said to end the world, but it was still a magic sword made to be wielded by
human hands. Even if it could create an embodiment of symbols of evil or sin, it could not
perfectly and purely summon one of the top-ranked gods of one of the world’s four largest
religions. There were said to be ten different avatars, but summoning a chaotic and
indistinguishable amalgam for a few seconds had been the limit of that sword.

Even so, the level of power had been incredible.

Demon King Surtr slowly collapsed to the side. That giant violently crushed a great
amount of snow and conifer trees while disappearing as if dissolving into the air. Kamijou
and Marian had been close by before, but she saw them slide off Surtr’s back in the
distance. They had only survived because Vishnu Avatara had prioritized the greatest evil
first. If the manifestation had lasted even a second longer, they too would have been
roasted as an element of conflict.

-Shinyaku Toaru Majutsu no Index Volume 10 Chapter 13 Part 7