Magic Conversion Potion and Another Attack (Part 2)

Warlock tapped his fingers lightly against the tabletop, his habitual gesture when thinking.

"Twenty-four hours," he rasped, his voice hoarse and slow, like sandpaper grinding against stone. "From the magic decay curve, the effective protective time a single grain of sand's powder can maintain is roughly ten to twenty-four hours, depending on the user's magic base. First and seventh years—their base is low, so maybe nine hours. Seventh years, high base, perhaps up to twenty. This variable—needs to be written in the manual."

Madara glanced at him. "Acceptable. You handle optimizing the activation mechanism of the protective charm. The prototype sample activates automatically, relying on the potion's magic circulation system to sense and trigger itself automatically. But for mass production, we need a more stable trigger mechanism. Use the user's heartbeat as the trigger signal. The petrification magic's energy shock will temporarily change the heart's electrical signal frequency; if the frequency change exceeds fifteen percent, the potion activates automatically. You will build this mechanism."

Warlock's light-blue eyes brightened slightly. That brightness was not excitement, but rather a more professional concentration akin to I love this kind of technical challenge.

"Heartbeat frequency monitoring," he muttered, tapping his fingers faster on the tabletop. "We can achieve it through magic resonance. Embed a miniature resonator inside the potion's magic circulation system, with the frequency set to the range of a normal person's resting heart rate. When the heartbeat frequency change exceeds the threshold, the resonator falls out of balance, triggering the release of the dissolution field."

"Do it," Madara said.

Carlisle kept his head lowered, staring at his own fingers. He did not look at the magic structure image, he did not look at Madara, and he did not look at the other three people. His gaze fell upon the un-washable black stains