The scroll was a key to an entirely new school of combat. For days, Ren did not leave his room. He committed the diagram of the human Aetheric circulatory system to memory, studying it with an intensity that surpassed even his research in the archives. This was not abstract knowledge; it was a schematic for the very weapon he was being taught to wield.
The art of "Thunder's Echo" was a terrifying concept. It was not about overwhelming an opponent. It was about hijacking them. It required him to project a resonant frequency so perfectly attuned to another person's Spirit Soul that he could influence, and eventually control, the flow of Aether within their own channels. It was the ultimate violation, a puppeteer's art disguised as a martial technique.
He began his practice not with an application of force, but with an act of listening. He would sit for hours, his chameleon's cloak active, and simply extend his senses toward the main academy grounds. He learned to filter out the ambient noise, focusing on the distinct Aetheric signatures of individual students as they practiced. He learned to identify the unique "hum" of a fire-aspected soul, the steady, rhythmic "thrum" of an earth-aspected one.
"The old fool teaches you the art of a parasite," Zephyrion's voice commented one evening, his tone a mixture of disgust and grudging respect. "This is a lesser form of the Raijin art of 'Dominion'. We did not need to listen to our enemies' pathetic songs. We would simply impose our own, our thunder drowning out their whispers until their souls shattered from the dissonance. His way is subtle. Cunning. The way of an assassin, not a Sky-Lord. But it is a start."
The spirit's words, as always, provided a new layer of understanding. The Elder was not teaching him to be a warrior. He was teaching him to be a ghost who could possess the living.
After a week of passive listening, Ren began the active phase. He needed a target, a moving, living system to practice on. He found one in the academy's practice dummies. They were simple constructs, animated by a low-grade, generic Spirit Core. He spent days projecting fine, resonant threads of his will at them, learning to match the frequency of their simple Aetheric cores.
His first attempts were clumsy. He would miscalculate the frequency and his resonant "echo" would either dissipate harmlessly or, in one memorable instance, overload the dummy's core, causing its limbs to flail wildly before it collapsed in a heap. He was learning to be a puppeteer, and his first puppets were breaking their strings.
He needed a real partner.
The opportunity came unexpectedly. He was walking back from the refectory when Joric, the hulking brawler from his first spar, fell into step beside him.
"Ren," Joric said, his voice hesitant. "I was wondering… could you… show me that thing you did? The punch. The one that beat me."
Ren stopped. "It was a simple trip."
"No," Joric shook his head, his expression serious. "Not the trip. The other thing. The thing you did to Sylas Drogan. The thing that made his shield just… stop." He looked at Ren with the earnest curiosity of a pure martial artist. "I want to feel it. I won't tell anyone. I just… I need to understand."
It was a perfect opportunity. A willing, powerful, and relatively simple Aetheric system to practice on.
They went to a secluded corner of the training grounds. "Hit me," Ren said simply. "Your Stone Fist. Your strongest one. But don't hold back at the last second."
Joric, looking confused but determined, nodded. He took his stance, his fists glowing with their familiar, muddy-yellow Aether. He roared and charged, throwing a powerful, straightforward punch aimed at Ren's chest.
Ren did not move. He did not prepare a defense. He simply watched the glowing fist approach, his senses locked onto the flow of Aether from Joric's soul, through his channels, and into his fist. He had listened to this specific "song" before. He knew the key.
In the split second before impact, Ren unleashed the Echo.
He projected a single, silent pulse of resonant will, perfectly harmonized with Joric's own Aetheric frequency. The pulse shot up Joric's arm and into his spiritual channel like a ghost in the river. It did not block the channel. It did not damage it. It simply introduced a new command: Halt.
Joric's eyes went wide. The brilliant earthen glow around his fist vanished as if a switch had been flipped. The immense power he had gathered dissipated instantly, leaving him with nothing but a normal, physical punch. Ren took a single step back, and the powerless fist sailed harmlessly past his chest.
Joric stared at his own hand, his face a mask of utter disbelief. He had felt his own power, his connection to his very soul, be commanded by another. He felt no pain, no injury. He had simply been… turned off.
"How…" Joric stammered, his voice trembling. "How did you do that?"
Ren looked at the terrified boy, then at his own hand. He now possessed an art that could strip a Spirit Master of their power with a single, invisible touch. It was the perfect weapon for the quiet war he was now fighting. A whisper that could silence a roar.