You Must Never Do This

Regulus looked down at the jar on the table; in the market, the jar alone would fetch a high price.

In the past two years, Slughorn has been attending classes, teaching Potions, Potions never missing a single Slug Club party. He's been going wherever he wants during holidays, and he was even taken on a tour of the Malfoy family's wedding.

Maintaining a network of contacts that spans most of the Europe Wizarding World is a full-time job in itself.

But two years have passed, and the idea he casually mentioned to Slughorn back in freshman year didn't seem to have any chance of coming to fruition.

Unexpectedly, the old man spent two years memorizing the recipe and went to great lengths to make it, consulting books, asking for help, finding materials, and experimenting with the proportions.

Anyone would be moved by this.

Regulus picked up the jar, turned it over in his hand, and ran his fingers along the edge of the sealing wax.

This kind of Potions is so different from the UK approach, and no one in continental Europe has ever been heard of making it; it's like starting from scratch.

Moreover, since it's something that enhances physical strength and power, the fact that the professor could produce it means that the side effects have been completely resolved, and it's a mature product that can be used directly.

"Professor," Regulus looked up, his tone sincere, "Something like this must be a great achievement for you, right?"

"It's not much of an achievement, just a bit of work," Slughorn waved his hand, his eyes crinkling with a smile, his round face full of pride. "But it's certainly one of a kind."

He picked up his teacup, took a sip, and looked at Regulus: "This medicine is rare and difficult to obtain, but it's not over yet."

Regulus raised an eyebrow.

Slughorn leaned forward, resting his hands on the edge of the table, his stomach against it. "It's a mature product now. Applying it can strengthen the body, it has no side effects, it can be preserved, and it can be used directly. On this level, it has reached its peak."

But this foundation can be further developed; it can serve as a base ingredient for another top-tier Potions, a direction completely different from physical enhancement.

Regulus's heart skipped a beat. The base, adding things on top, the old man's words had a hidden meaning.

He sat upright, his posture relaxed, and continued his flattery, "Professor, just this finished product..."

Slughorn waved his hand to interrupt him, his expression darkening and his tone changing.

"This medicine has a unique characteristic: after penetrating the skin, it forms a very thin layer on the body's surface that can hold certain substances."

Regulus asked, "What are you carrying?"

Slughorn looked at him for a moment, but still didn't answer. He continued, "I have a few things to tell you, listen carefully."

"You said, Professor."

"The first step, the materials," Slughorn's smile vanished completely, his brows furrowed, and the wrinkles at the corners of his eyes deepened. "Seven main ingredients and three auxiliary ingredients."

In the fissures of the Arctic Permafrost Layer, there grows a type of moss called White Night Frost Moss, which can only be harvested for two weeks a year. Once the sun's angle changes, the moss loses its activity and must be sealed immediately after harvesting. If the temperature rises even by one degree on the road, the material is ruined.

Regulus listened quietly.

"The second type Silver-Patterned Tree Bark from the Moon Mountains of the Uagadou tribe in West Africa. That tree only grows on the shady side of the Moon Mountains, and its bark is only peeled once a year under a specific lunar phase. The tree is still alive after the peeling, but the bark cannot be peeled again for three years. It is not available on the market; you have to trade it with the tribe, and they decide what you trade it for."

Slughorn held up another finger. "The third type is mineral powder from the Tonga Trench Volcano in the Pacific Ocean. It must be collected within 72 hours of Volcano eruption during the Southern Hemisphere winter, when the water temperature is below -2 degrees Celsius. If the timing or temperature is slightly off, the powder will lose its activity."

He paused to catch his breath, picked up his teacup to moisten his throat, and continued, "The fourth type is the bone powder of deep-sea horse carcasses from the north coast of Scotland. They must be old deep-sea horses that died naturally and were buried in the seabed mud for at least fifty years after their death."

The fifth type is the pith from the Thunderbird tail feather Andes Mountains the high-altitude Andes Mountains. It is the pith in the middle of the feather, and only a small section can be taken from each feather.

The sixth type is Volcano crystals from the Iceland tundra. These must be collected in the third month after a Volcano eruption; if collected too early, crystals will not form, and if collected too late, the crystals will begin to weather.

The seventh type, and the most obscure of the main ingredients, is the sulfide deposits from hydrothermal vents on the North Sea seabed. These must be collected during the intervals between eruptions; the water temperature is too high during eruptions and too low during the intervals. You have to time it perfectly, capturing those few minutes in between.

Regulus raised one eyebrow upon hearing this.

The Arctic Circle, West Africa, the Pacific Ocean, Scotland, the North Sea, the Andes, Iceland —seven main ingredients, circling the globe, all under the right season, the right time, and the right conditions.

"Three auxiliary ingredients," the professor continued, "Are coral bone powder from the depths of the Indian Ocean, which must be obtained outside of coral spawning season; Obsidian fragments from the bottom of glacial lakes at high altitudes in the Alps, which must be collected when the lake is completely frozen; and a third ingredient is my own blending agent, the formula of which is with me and not to be shared."

"These things," Slughorn's tone suddenly became serious, "You absolutely must not collect them."

Regulus looked at him in surprise.

The professor withdrew his hand, placed it on his stomach, and leaned back. "Don't go. Once you start collecting, you'll want to collect them all, and once you do, you'll want to endure the long wait."

He paused, looking at Regulus's face.

"You absolutely mustn't collect them all. Once you do, and boil them together with this ointment, its effect will change. It will no longer be something that strengthens physical strength; it will become something else entirely."

Regulus gave a very slight twitch at the corner of his mouth, already roughly understanding what the professor was talking about.

"The second step," Slughorn didn't give him a chance to reply, "The cooking time."

"The Magic Power activity of some materials is related to the position of stars. If the celestial alignment is wrong, everything brewed will be ruined. There are very few suitable windows for this; the most recent one is during the heliotropic conjunction of Sirius and Procyon."

Regulus's lips moved, but he didn't ask any further questions.

His Astronomy knowledge was sufficient; this constellation occurred around the winter solstice, three days before Christmas.

This timing coincided with the message Lucius had given him: Voldemort wanted to see him on Christmas.

coincide?

Slughorn noticed Regulus's change in expression but ignored it, continuing, "Even if you manage to gather all the ingredients and are really planning to brew it, even if you accidentally put them all together, don't brew it at this time of year under these celestial signs."

His voice rose slightly. "Otherwise, the medicine won't be the same medicine anymore; it will truly be different from the original."

What could Regulus say?

He nodded.

"The third step," the old man tapped the table lightly, indicating the crucial point, "Is that if you actually manage to gather the ingredients and brew the medicine within those three days of the winter solstice, you absolutely must not rely on your strong will and powerful soul to extract your own soul characteristics and fuse them into that pot of medicine."

He stared at Regulus, slowing his speech. "You absolutely mustn't do that."

Regulus blinked; he had a strong sense of déjà vu.

"If you do that, this medicine will coat your soul with a shell. It's not a bad thing; it can block some external Magic Power, but it will also isolate your soul from the outside world."

Regulus's gaze fell on the jar on the table.

Now that things have been said to this extent, what else is there to misunderstand? Dark Mark.

The mark Voldemort branded on the Death Eaters's left forearm was certainly not just a simple tattoo.

That thing is connected to the soul; Voldemort could use it to summon his minions, sense who was where, who was still alive, and who was dead.

The professor's indirect approach, rather than stating things explicitly, is what he meant by beating around the bush.

Even though this office was one of the most private places in Hogwarts, even though the old man had just pushed a jar of ointment that took two years to make in front of him, and even though he had told him a lot of things he absolutely could not do.

Regulus was silent for a moment, then raised his head and nodded slightly.

Seeing that Slughorn understood, Regulus visibly relaxed, took a Candied Pineapple from the plate, popped it into his mouth, chewed it a couple of times, picked up his teacup, took a sip, and moistened his throat.

"Step four, drawing."

He put down his teacup, wiped his mouth with a handkerchief, and his tone returned to its previous rambling manner. "Even if you really gather all the materials, really brew it under that star sign, and really accidentally extract your own soul characteristics and put them in, you absolutely must not draw it on your body in that way."

The old man drew a closed circle in the air with his hand. "It's a method of painting that involves spreading out layers, covering the whole body, with patterns connecting to patterns without leaving gaps between them. Don't do it that way."

His expression brightened, and his tone carried a humorous emphasis. "Otherwise, it will form a complete shell around you, a sealed shell, covering your entire soul, so that nothing from the outside can touch your soul at all."

Regulus nodded obediently, his posture upright and his expression serious. "I understand, Professor. I certainly won't do that."

Slughorn looked at him, a smile finally appearing in his eyes, "The fifth step, solidification."

"After application, the medicine must remain on the skin for a specific period of time. During this time, it must not be disturbed by any external force, cannot come into contact with water, cannot be used to Spellcasting, and must not experience any emotional fluctuations."

Throughout the entire day, from beginning to end, the surrounding environment must be absolutely quiet, and you yourself must be absolutely still.

You absolutely must not do anything unnecessary during this period; if you interfere with the solidification process, the previous four steps will all be wasted.

I mean, please don't do that.

He paused to catch his breath, and then said in one breath, "If you really go this far, if you really build a complete, closed shell around your body, if you really put this shell over your soul..."

During this period, you absolutely must not touch water, Spellcasting, or allow your emotions to fluctuate.

Otherwise, this shell would truly form, truly align completely with your soul, and you wouldn't be able to tell it from the outside.

His eyes kept glancing at Regulus's face, glancing once after each sentence and once after the last sentence.

Regulus looked at Slughorn and smiled. "Thank you, Professor. I understand."

Slughorn's shoulders relaxed completely, and he leaned back in his chair, a smile returning to his round face. He patted his stomach, his tone much more relaxed.

"Good, good."

His tone lightened. "Don't take it too seriously. Even if you manage to gather all these things, really get through the process, really get rid of the shell, really align with the soul, and it's indistinguishable from the outside, there's nothing to worry about."

He looked at Regulus, a smirk playing on his lips. "At your current level, peeling off this shell would be easy for you."

Regulus looked at the old man's round face and his eyes, which were narrowed into slits, and the corners of his mouth curved upwards.

He picked up the jar from the table, put it in the inner pocket of his robe, and patted it. "Professor, I'll take this."

"Take it if you want," Slughorn waved his hand casually, "Just don't let me find out what you do with it."

He reached into the dish, took another Candied Pineapple, popped it into his mouth, chewed it a couple of times, wiped his fingers with a handkerchief, and looked out the window toward the Black Lake.