Amputation surgery

Although William was indeed interested in Forseti's pair of wings, the secret techniques he promised were not offered in jest.

"Here is my 'Theory of Space-Time', and this other book is a corresponding secret technique. As for the name, you can choose it yourself; I'm not fond of naming things." William casually tossed two paper books onto the table.

Strictly speaking, if Forseti understands these two books, he could easily cross space and reverse time.

However, even after many years of study, William could only reverse time by a maximum of 10 years.

That is, bringing the entire universe back to 10 years ago.

Reversing time is an extremely formidable skill,if Forseti could reverse even a moment of time, that would be quite impressive.

In Divine Realm battles, many outcomes are decided in an instant.

The ability to reverse or pause time, what impact would that have on the outcome of a battle?

It's unimaginable.