This was the last method Satoru could think of.
When Ice Barrier was used on oneself, it relied on ice said to be "close to absolute zero," its unparalleled hardness resisting outside harm.
But to ensure the caster's safety, The Book of Medivh clearly stated that the spell's duration had to be set before casting. It absolutely could not exceed ten seconds, and the interval between uses could not exceed thirty seconds.
But what if its extreme cold was used to make an "ice coffin"?
Someone gravely wounded beyond healing but still clinging to life could be directly sealed in Ice Barrier. The extreme low temperature would reduce the injured person's bodily functions to their lowest level, sending them into a suspended state even deeper than "hibernation."
Naturally, under such rapid freezing, any injuries would not continue to worsen and would remain exactly as they had been at the moment of freezing.
And because the caster would remain outside the ice coffin, its duration could be controlled and ended at any time.
But even so, it could not last too long—remember that unlucky inventor of Ice Barrier who froze himself for several years and died?
In theory, ultra-low-temperature freezing could preserve someone in suspended animation for a very, very long time—like Captain America?
But a critically wounded person obviously would not have Captain America's absurd physical constitution. Even suspended animation consumed something, however little, and the longer the freezing lasted, the lower the chance of revival.
And the good news was that Konoha's strongest Medical Ninja, Nawaki's sister Tsunade, was at the frontline fortress.
Although Satoru was not sure whether Tsunade's current mastery of Medical Ninjutsu could save Nawaki—
After all, in the original story, Tsunade had failed to save the jonin Dan Katō, whose injuries had been roughly similar