He discovered regeneration six weeks into the practice phase, on a morning when he was tired and his pool was running low from weeks of daily draws.
The subject was a Bark Lizard — his most frequent test case by now. This one had lost most of its tail in a territorial dispute. Not a partial wound. A clean removal at the midpoint.
He healed the stump first. Closed the end, addressed the tissue damage, stabilized the structure. Seven minutes. Clean work, well within his current ability.
Then, on an impulse more than a plan, he kept going.
Past closure. Past stabilization. He directed the healing sense outward from the stump end — not into existing tissue but beyond it, toward where the rest of the tail should have been.
The healing magic followed.
It reached past the body's current edge and began building from a template — not creating from nothing, but reading the body's own information about what that missing tissue was supposed to look like and using it as a blueprint. Slowly. At enormous cost. The pool dropped faster than anything he had yet attempted. But the tissue grew. Segment by segment, scale by scale. Forty minutes of work produced approximately an inch of new growth before he ran out and had to stop.
He released the lizard, which bolted immediately and thoroughly.
He sat with what he had found.
He could regenerate. With enough energy and time, he could grow back what had been lost.
He thought about Lyra's lungs. The years of accumulated scarring. The layers of damage-healed-wrong-then-damaged-again that the chronic infection had been quietly building since before he arrived. The healing sense had already shown him what that tissue looked like. He knew it was bad.
He thought: I can address that. Not just the infection. The damage it has caused.
He thought: I need to be considerably better at this before I touch tissue that belongs to someone I love.
He went back to practicing on forest creatures.
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Two months into the practice phase the real problem became clear.
He was, by this point, a competent healer of things he could locate. Surface wounds, internal injuries with identifiable sites, discrete breaks and tears. His technique had improved enough that a second attempt at tail regeneration took twenty-two minutes and produced two and a half inches of growth. He estimated another month of practice would produce a complete tail in a single session.
None of this was relevant to Lyra.
Because Lyra's condition was not a wound. It had no single site. It was a chronic infection — a population of organisms distributed through the architecture of her lungs in a pattern he could not map, at varying concentrations and varying stages of activity, in complex interaction with an immune system that had been fighting them for years. You could not point at it. You could only find it if you could see inside.
He had extended the healing sense into her lungs twice while she slept, briefly and carefully. He knew things were wrong. He could not tell where, specifically, or how wrong in each location. Without that map he could not treat her precisely. He would miss the worst areas, or overwork the less affected ones, or both.
He needed the diagnostic technique he had watched the healer use from his cradle — the pulse of flat light that had briefly illuminated the patient's interior. He had stored it as a behavioral observation without understanding the mechanism.
He had been stuck on this for four weeks when Shadow killed the Thornback Boar.
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The Thornback Boar was large and old, and the kill had required a multi-point construct he had spent three weeks developing in preparation. Shadow at Level 12 could manage it. Not comfortably, but reliably.
The absorption was the richest single event since he had started hunting the deep forest. Old creatures accumulated a great deal. The boar had lived long enough to have a history of encounters with humans, territorial disputes, seasonal patterns — years of a life that had been long and varied and observant. Arthur processed it over four days, going through it carefully rather than extracting the summary and releasing the rest. The most valuable information usually lived in the fragments.
On the third day he found it.
Not prominently stored — not a vivid or recent memory. An old encounter, filed under the category large territorial animals maintained for unusual human behavior near their range. A clearing, approximately twenty years past. Two humans — one injured and still, one kneeling over the first with glowing hands. The boar had watched from the tree line, assessed, decided interesting rather than dangerous, and moved on after three minutes.
Three minutes was enough.
In those three minutes: the kneeling human had placed both palms flat on the injured person's chest. The light at his hands changed — from the warm focused glow of healing to something broader and flatter. A pulse of that flatter light moved into the body. And the injured body illuminated briefly from within, not uniformly, but in a pattern that corresponded to its interior structure rather than its surface.
The healer's eyes had been closed the whole time.
His expression was not the expression of someone projecting power outward. It was the expression of someone listening.
Arthur understood immediately.
A diagnostic pulse was not a projection. It was a question asked of the body in a language the body could answer. You sent it in and it came back carrying the signature of everything it had touched, and you read the return not by seeing but by interpreting pattern — the way sonar worked, the way echolocation worked, the way any system worked that built a picture from what came back rather than from what was directly visible.
He had been building toward this without knowing it. The understanding arrived complete.
He spent the fourth day building the mechanism from what he had seen.