The Room of Requirement gave him a workbench. Stone surface, good lighting, a single chair. Rowan hadn't asked for anything beyond space and quiet, and the Room had understood. He set the box on the workbench and sat down.

  He'd been thinking about this all day. Classes had blurred together. He couldn't have said what Professor Shah taught during Astronomy or what notes he'd taken in History of Magic. His mind kept circling back to the box, to the keystone, to Revelio Complexum.

  Now he was here, ready to find out if it worked.

  Rowan raised his wand and cast.

  "Revelio Complexum."

  The air above the box shimmered. Layers of light materialized. Thin, translucent threads weaving through each other in patterns that made his eyes water if he stared too long. Deep blues, violets, threads of pale gold, all intersecting and branching across the box's surface like veins of light.

  He pulled his journal close and began sketching.

  The outermost layer was the anti-Alohomora ward he'd already identified. Beneath it, a series of detection charms. Proximity wards, intent-reading spells, things designed to alert someone if the box was tampered with. Beneath those, older layers. Preservation enchantments keeping the wood from rotting, the contents from degrading. Time wards of impressive complexity.

  And at the very center, one thread brighter than all the others. Gold, pulsing with a slow, steady rhythm.

  The keystone.

  Rowan traced its connections carefully. Every other enchantment in the structure fed back to it. The anti-Alohomora wards drew their strength from it. The detection charms were anchored to it. Even the preservation spells cycled through it.

  A Durability Anchor. He recognized the pulse pattern from the curse-breaking texts. A charm that made other enchantments permanent, resistant to natural magical decay. Without it, spells this old would have faded to nothing centuries ago.

  Which meant the Headmistress who'd sealed this box had built it to last. She'd intended it to stay locked for a very long time.

  Rowan studied the anchor's structure for another twenty minutes, committing its shape and connections to memory. Then he set down his journal and picked up his wand again.

  Finitus Permanens. The counter-charm for Durability Anchors. He'd read about it last night in the restricted section, practiced it once on a ward he'd conjured himself. It had worked cleanly. The anchor dissolved, the remaining spells faded within seconds.

  That had been a ward he'd created five minutes earlier. This was one a Headmistress had crafted three centuries ago.

  He aimed carefully at the golden thread. At the center of the pulse, where the anchor drew its power.

  "Finitus Permanens."

  The golden thread flickered.

  For a moment, nothing else happened. Then a ripple spread outward from the center, racing through the web of light. The detection charms flickered and died, the anti-Alohomora wards sputtered and collapsed, the preservation spells dimmed as their sustaining power drained away.

  Layer after layer fell away, like peeling skin from old fruit.

  The box's surface went still. The ancient carvings stopped their restless shifting, and the weight Rowan had felt pressing against his magical senses, the weight of centuries of protective magic, simply vanished.

  The lid was free.

  Rowan sat for a full minute, staring at it. Then he reached forward and lifted the lid.

  Inside, wrapped in oilcloth that had preserved its contents perfectly, were scrolls. Old ones. Parchment yellowed with age, the ink faded but still legible. Five of them, each sealed with wax bearing a sigil Rowan didn't recognize.

  Beneath the scrolls, nestled in a small clay pot with a tight-fitting lid, was a living specimen. Rowan lifted the pot carefully. Through a crack in the lid, he could see a faint bioluminescent glow, pale blue-white, pulsing gently in a rhythm that reminded him, oddly, of a heartbeat.

  A fungus. Unusual, clearly magical, and somehow still alive after three hundred years in a sealed box.

  He set the pot aside and turned to the scrolls. Breaking the first wax seal, he unrolled it carefully.

  The handwriting was precise and elegant, the ink a deep burgundy that had held its color remarkably well.

  These are the notes of Phyllida Spore, compiled during my final years at Hogwarts, and sealed by my own hand against the day when someone worthy might need them.

  Rowan's breath caught. Phyllida Spore. The name was familiar. One Thousand Magical Herbs and Fungi was a standard Hogwarts textbook, attributed to her. She'd been Headmistress of Hogwarts. These were her personal research notes, sealed by her own hand and entrusted to the centaurs for safekeeping.

  He read on.

  The scrolls detailed Spore's research into a particular species of magical fungus. The very specimen sitting in the clay pot beside him. The fungus fed on ambient magical energy, concentrating it, and when consumed by a wizard, it transferred that concentrated magic directly into their core.

  Permanently.

  The effect was explosive. A single dose could multiply a wizard's magical capacity several times over. The fungus essentially accelerated magical core development by years, or in some cases decades, in a matter of hours.

  But the organism had a severe limitation. The entire mycelial network functioned as a single interconnected system. It could grow larger under the right conditions, but it did not reproduce. One organism, one dose. Spore had learned this the hard way.

  Her notes documented five wild colonies found at a site in the Forbidden Forest:

  Division of Colony 1 — both halves expired within hours. Colony 2, same result. Colony 3 administered to test creature in full — enhancement confirmed, severe dark corruption observed. Colony 4 administered in partial dose — no effect. Remainder expired. Returned to forest site. No regrowth. Conditions appear irreversibly disturbed by prior extraction.

  The fifth colony sat in the clay pot beside him. Spore's final note on the matter was underlined twice: The specimen cannot be divided. To use it is to use all of it.

  Rowan read the warnings carefully. They took up an entire scroll by themselves.

  The fungus carried a dark magical signature. The transformation it caused, forcing rapid core expansion, drew on dark magical principles. It wasn't cursed or malicious, but unmitigated consumption would overwhelm the core with dark-tainted energy, potentially killing the wizard outright or corrupting them entirely.

  The solution was a stabilizing potion. Spore had developed the formula from her analysis of the corruption, but her colonies were gone before she could test it. The final version required seven ingredients, precise temperatures, and exact timing. It should neutralize the dark signature, allowing the core to absorb the enhanced magic safely.

  Or at least, as safely as fundamentally reshaping your magical capacity could be.

  Rowan copied every detail into his journal. The composition, the growth requirements, the stabilizer recipe, all of it. He read each scroll three times before moving to the next.

  The fifth and final scroll was shorter than the others.

  I leave these notes because I believe the wizarding world needs wizards who are willing to push beyond what is comfortable and expected. The fungus is dangerous. The process is painful. But the result—a wizard with the capacity to truly do good—is worth the risk.

  To whoever finds this: be brave. Be precise. And understand what you are becoming.

  Enjoying this book? Seek out the original to ensure the author gets credit.

  — P. Spore

  Rowan set the scroll down and looked at the clay pot. The pale glow pulsed steadily through the crack in the lid.

  He needed more information. Spore's notes were thorough, but he wanted to cross-reference everything he could before attempting anything. The fungus's growth requirements, its magical properties, how it interacted with other magical organisms. There had to be additional documentation in the library, even if it wasn't in the restricted section.

  He returned to the restricted section the next evening, permission slip still valid. Madam Scribner glanced up as he entered, noted his direction toward the east wing, and said nothing.

  Rowan searched methodically. Herbology texts, magical creature compendiums, ingredient catalogues, theoretical treatises on magical biology. He pulled book after book from the shelves, scanning indices, flipping through pages.

  He found nothing. The species didn't appear in any catalogue he could find. Either it was so rare that no one else had documented it, or someone had deliberately scrubbed the records.

  He was about to give up. Three evenings of searching, and he had nothing beyond what the scrolls themselves contained. Then his hand closed around a slim, leather-bound book tucked between two larger volumes on a lower shelf.

  It looked unremarkable. No title on the spine, just worn brown leather. But when Rowan pulled it out, it sat in his hand with an odd weight. Not dangerous, just significant, as if it mattered more than it looked.

  He opened it.

  The pages were filled with a single hand, cramped and hurried, covering every available inch of parchment. A journal rather than a proper book, a collection of notes made by someone who'd been thinking very fast and writing even faster.

  The first page bore no name. Just a date. 1473. And a single line:

  The vaults beneath the school hold something that must never be opened. I have spent forty years trying to understand what, and I am no closer than when I began.

  Rowan turned the page.

  The notes were dense, rambling, circling back on themselves. References to "the corruption beneath," to "doors that should not have been built," to "a darkness older than Hogwarts itself." Calculations that seemed to mix runic theory with a discipline Rowan couldn't quite identify.

  And then, near the middle of the journal, a passage that stopped him cold:

  I have tried every method of analysis available to me. Wards, divination, arithmantic modeling—none of it penetrates the vault doors. The magic beneath is too old, too deep, too fundamentally wrong for conventional approaches.

  Perhaps the answer is not in analysis at all. Perhaps it is in riddle.

  What has no door, yet bars the way? What holds treasure but refuses to give? What speaks without a voice and guards without hands?

  The answer is not the vault itself. The answer is the thing that plays.

  Rowan read the passage three times.

  The thing that plays.

  He didn't understand it yet. The riddle sat in his mind like a stone dropped into water, the ripples spreading outward, disturbing what lay beneath the surface while the bottom remained invisible.

  He copied the passage into his journal word for word, then continued reading. The remaining notes grew more erratic, the handwriting deteriorating as though the writer had been increasingly desperate. The journal ended mid-sentence on the final page, the ink trailing off into nothing.

  Rowan closed the book and sat for a long time in the quiet of the restricted section, thinking.

  The cursed vaults. He'd heard rumors. Every student heard them eventually. Dangerous old magic locked beneath the castle. Most students dismissed it as ghost story material.

  This journal suggested otherwise.

  But that was a problem for another day. Right now, he had a fungus to grow.

  Back in his dormitory, Rowan pulled out Spore's notes and reviewed the cultivation requirements. The fungus required precise conditions: specific soil composition, controlled magical resonance levels, temperature between sixty and sixty-five degrees, and exposure to moonlight for at least four hours per night.

  Greenhouse Three at Hogwarts met most of these requirements. The soil beds were rich with magical nutrients, the temperature was maintained by warming charms, and the greenhouse's glass walls allowed moonlight through on clear nights.

  But he couldn't just start growing an unknown magical fungus in a school greenhouse without raising questions.

  Professor Mirabel Garlick was the obvious person to approach. She ran Greenhouse Three with meticulous care and genuine passion for magical plants, the kind of enthusiasm that lit up her face when she encountered a new specimen.

  Rowan found her the next morning after Herbology, lingering in the greenhouse as the other students filed out.

  "Professor Garlick, I was wondering if I could speak with you about a research project."

  Garlick turned, wiping soil from her hands on her apron. She was a small woman with kind eyes and perpetually dirt-stained fingernails, and she looked genuinely pleased to be asked.

  "Of course, Mr. Ashcroft. What sort of project?"

  "I acquired a specimen of an unusual magical fungus over the summer. I'd like to study its growth patterns, but I don't have the facilities in my dormitory. I was hoping I might be able to use space in Greenhouse Three."

  "A fungus?" Garlick's eyes sharpened with interest. "What species?"

  "I'm not entirely certain. I haven't been able to find it catalogued anywhere." Rowan produced the clay pot from his bag carefully. "I bought it from a specialist shop in Diagon Alley. The seller couldn't tell me much about it either."

  He lifted the lid just enough for Garlick to see.

  The pale blue-white glow pulsed gently in the dim light of the greenhouse. Garlick leaned in, her expression shifting from curiosity to quiet awe.

  "Oh," she breathed. "Oh, that's extraordinary. I've never seen bioluminescence like this in a fungal specimen. The magical signature is—" She pulled out her wand instinctively, holding it near the pot without casting, simply feeling the resonance. "Remarkable. Truly remarkable."

  Her expression shifted slightly. "Though... there's an unusual quality to the signature. It has dark magical properties. Nothing malicious, but the resonance pattern suggests it draws on darker principles than most flora. Where did you say you acquired this?"

  "A specialist shop in Diagon Alley," Rowan said. "The seller mentioned it was rare but didn't say anything about dark magic."

  "Dark properties don't necessarily mean dangerous," Garlick said, still examining the fungus with her wand. "Many perfectly legitimate specimens use darker magical principles. But it does mean we'll need proper containment protocols. A warded bed, careful monitoring." She looked up, her enthusiasm returning. "This makes it even more fascinating, actually. Controlled study of dark-principle flora is quite valuable."

  "I'd welcome the help, Professor."

  "Wonderful." Garlick was already pulling on her work gloves, her attention entirely captured. "Do you have growth specifications? Soil requirements, temperature, light exposure?"

  Rowan produced the notes he'd prepared. A carefully edited version of Spore's instructions, stripped of anything that might raise questions about their origin. Just the practical requirements, presented as observations he'd made himself.

  Garlick read them with growing enthusiasm. "Moonlight exposure, controlled temperature, high magical saturation in the soil. This is a lunar-cycle dependent organism. Fascinating. We can set it up in bed seven, the one with the best moonlight access."

  Over the next week, they worked together to establish the growing conditions. Garlick was meticulous and helpful, adjusting soil composition, monitoring temperature, even enchanting a small mirror to redirect moonlight on cloudy nights. She asked questions constantly. About where Rowan had found the specimen, what he hoped to learn, whether the seller had provided any documentation.

  Rowan deflected each one smoothly. The shop in Diagon Alley. A curiosity purchase. No documentation, unfortunately. The seller was informal about paperwork.

  Garlick accepted this without suspicion. Her focus was entirely on the fungus itself, which was growing steadily under the conditions they'd established. Within three days, the original specimen had spread across the soil bed, the pale glow intensifying as it fed on the greenhouse's ambient magical energy.

  "It's consuming magic at an extraordinary rate," Garlick noted one afternoon, examining the growth with careful measurements. "The magical saturation in this bed has dropped fifteen percent since we planted it. Remarkable metabolic efficiency."

  Rowan nodded, making notes. He was watching the growth carefully, checking it against Spore's specifications. The fungus was developing exactly as predicted. Fast, steady, and with increasing potency as it matured.

  By the end of the week, it was ready.

  His roommates went to bed at their usual times. Hector fell asleep quickly, as always. Lawrence read for another hour before setting down his book. Amit turned out his light without a word. Timothy was already snoring before eleven.

  Rowan lay in bed, listening to their breathing settle into the slow rhythms of sleep.

  At half past eleven, he sat up.

  The stabilizer potion was already brewed. He'd made it over three evenings in his abandoned classroom, following Spore's instructions precisely. Seven ingredients, exact temperatures at each stage, stirred counterclockwise during the cooling phase. The result was a thin, colorless liquid with a faintly sweet smell that he'd stored in a small vial.

  The fungus he'd harvested that afternoon, during his last visit to Greenhouse Three. All of it. The entire mycelial network lifted from the soil bed in one careful extraction, because that was what Spore's notes required. One organism, one dose. There was no way to divide it, no way to leave some behind and still have enough. He'd dried the whole specimen and ground it into a fine powder, which he'd stored in a separate vial.

  Two vials. That was all it took.

  Rowan moved silently to the bathroom attached to the dormitory. He locked the door, cast a silencing charm, and sat down on the cold tile floor with his back against the wall.

  He mixed the powder into the stabilizer according to Spore's instructions. Stir once, clockwise, wait thirty seconds for the color to shift from clear to pale amber. It did, exactly on schedule.

  He looked at the vial for a long time.

  Spore's warning echoed in his mind. The process is painful.

  Hecat's voice, too, unbidden. Overconfidence against the wrong opponent could get you killed.

  He was asking his own body, his own magical core, to change in a fundamental way. If Spore's notes were wrong, if the stabilizer formula wasn’t effective, if the dosage was off, if the fungus had changed in ways she hadn't predicted.

  Rowan drank it.

  The taste was nothing. Bland, slightly sweet, gone in a single swallow.

  For about ten seconds, absolutely nothing happened.

  Then his chest caught fire.

  It wasn't pain, exactly. Or rather, it was pain, but deeper than muscle or bone. It was his magic itself, the core of it, a part of him he'd never directly felt before, suddenly awake and screaming.

  The world went white.