%e8%91%ac%e9%80%81%e3%81%ae%e3%83%95%e3%83%aa%e3%83%bc%e3%83%ac%e3%83%b3%2c%e2%80%93%2craw%2c%e3%80%90%e7%ac%ac3%e8%a9%b1%e3%80%91%2c%e8%91%ac%e9%80%81%e3%81%ae%e3%83%95%e3%83%aa%e3%83%bc%e3%83%ac%e3%83%b3%2c%e2%80%93%2craw%2c%e3%80%90%e7%ac%ac3%e8%a9%b1%e Guide

: Frieren breaks the seal herself to finish the job. When Qual awakens and immediately fires his "ultimate" Zoltraak, he is stunned to find that Fern—a mere human child—effortlessly blocks it with a modern, standard defensive barrier.

: Eighty years ago, Frieren's original hero party could not defeat Qual. He had developed a revolutionary spell called Zoltraak —"Killing Magic"—which bypassed all contemporary human defensive magic and gear. Lacking a way to block it, the party chose to seal him away instead. : Frieren breaks the seal herself to finish the job

: Frieren explains to Fern that in the decades since Qual was sealed, human mages studied his spell. They eventually "standardized" it, incorporating its principles into humanity’s own offensive and defensive magic systems. He had developed a revolutionary spell called Zoltraak

The content refers to (Killing Magic), which is the third episode of the anime Frieren: Beyond Journey's End and corresponds to the early chapters of the manga. Story Summary: The "Killing Magic" Incident They eventually "standardized" it