The humans of this world all have the walker virus lurking within them; as long as they die or are bitten by a Walker, they will turn.
But he, as a soul from another world, logically should be free of the disease.
Could it be that when the Episkey charm is used to treat humans of this world, it's not just simply repairing flesh and blood, but instinctively fighting the viruses in their blood?
And when he casts it on himself, because there's no viral interference, the effect is better and the cost is lower?
"No, no, no, how is that possible! That's too far-fetched!" Louis quickly dismissed this overly whimsical guess.
Setting aside the fact that this hypothesis was baseless, judging solely from the magic settings in his memory, the main function of the Healing Charm in the HP system is to treat physical trauma.
He had never heard of it having detoxifying or anti-viral properties.
Furthermore, although he was healthy before crossing over, who could guarantee he hadn't been infected after being here for so long?
"Though, it's possible I misremembered the limitations of Episkey," Louis temporarily gave up, unable to find a clue. "But before figuring out whether I have the walker virus in me, I shouldn't jump to conclusions."
After clearing his thoughts, he focused his attention on the few charms he had currently learned.
He had only half-mastered Aguamenti, and Episkey was acting abnormally... Looking at it this way, the only ones that could be considered normal and not much different from the original effects seemed to be Scourgify and Wingardium Leviosa... right?
Louis recalled that "Scourgify" was just for cleaning, nothing special. As for the "Wingardium Leviosa"? Since it just makes things float, it should be about the same?
But at the thought of Wingardium Leviosa, a new confusion arose in Louis's heart.
That was, he discovered his magic talent seemed to be somewhat "elastic."
Or rather, like a "Schrödinger's Genius."
Logically speaking, ignoring the failed attempts of the first day, he was able to practice Wingardium Leviosa from scratch to the point of wandless non-verbal casting in less than two months.
While this was certainly due to the stimulus of the Apocalypse crisis and his adult soul's stronger comprehension, this speed and the final height reached were definitely not something an ordinary person could achieve, even among the Wizards at Hogwarts.
If Lord Voldemort came, he would probably praise him, saying, 'How terrifying, this child must not be allowed to live!'
Even if he couldn't compare to those transmigrator predecessors who had Fiendfyre protection and could spam Avada Kedavra at will, in the original HP world, his talent for Wingardium Leviosa could be considered that of a genius, right?
But the problem was—the process of learning all his charms was exceptionally difficult!
When Louis cast spells, he always felt the magic output was intermittent, like being separated by a layer of frosted glass, hazy and difficult to control precisely.
Content that those young Wizards in the original work could basically master in one class, he would practice repeatedly with the textbook for several days and still might not successfully cast it.
And this was under the guidance of a first-year textbook with detailed illustrations and tutorials!
If he were a magic genius, why was he struggling so much with even these basic spells?
Actually, this included Wingardium Leviosa itself.
Aside from the momentary smoothness of the first successful cast, during the long period of practice afterward, he had also felt that sense of jerkiness and obstruction.
But he didn't know when that sense of obstruction started getting weaker and weaker.
Was it the first time he used Wingardium Leviosa to control a stone and crush a Walker's head? Or when he used a steel spike to pierce a Walker's eye socket in the hospital? Or... when he tried using Wingardium Leviosa to lift himself and "fly on a board"?
It seemed that after those few times of using Wingardium Leviosa in actual combat, his control over the spell began to advance by leaps and bounds, his proficiency soared, and he eventually reached the realm of wandless non-verbal casting as if it were only natural.
Could it be... that he only possessed extraordinary talent in this one spell, Wingardium Leviosa?
Louis rubbed his chin in thought. Such cases seemed to exist in the original HP books.
Some Wizards seemed naturally endowed with a stronger understanding of specific magic or individual spells due to their personal will and experiences. For example, Harry with "Expelliarmus" and Lockhart with "Obliviate."
Could he be in the same situation? A natural "Wingardium Leviosa prodigy"? Plus, to save his life, it was his most used spell, so practice made perfect?
This explanation... wasn't exactly illogical. But he always felt things weren't that simple.
What exactly was that "sense of obstruction" when casting? Why did only Wingardium Leviosa finally break through?
"Too few clues, I'll just note it down for now and discuss it later."
Louis shook his head, putting these temporarily unanswerable questions out of his mind.
Whatever the reason, it wasn't something he could figure out now. The urgent priority was still to master a few more practical magic spells as quickly as possible.
After all, he had changed worlds; it was possible for magic effects or learning methods to change. The most crucial thing right now was to improve his strength and survive first.
Thinking of this, he returned his attention to that first-year textbook, The Standard Book of Spells, Grade 1.
His short-term goal was to master two low-level but very practical spells.
One was Petrificus Totalus, used to enrich his offensive means.
This was one of the few spells where he could feel clear magical feedback during practice. Moreover, it was highly practical whether dealing with agile living people or tireless Walkers.
He had even thought of a disguise plan: he would carry some pungent potions, homemade smoke bombs, or even some blow darts with him.
When the time came, he would have his own people wear masks or drink the "antidote" beforehand, and while he cast Petrificus Totalus, he would throw these items at the target!
This would create the illusion that "I'm using drugs or special weapons to incapacitate the opponent."
Although some details needed refinement, such as how to explain if a teammate also wanted to use them, these could be figured out later. Overall, if he could learn it, this would undoubtedly be a powerful control method that could be used openly while disguised.
Anyway, I'm already a "medical genius" in everyone's eyes; it should be reasonable to moonlight as a "Breaking Bad" chemist, right?
The other one he had to conquer was a seemingly basic but actually miraculous lifestyle spell in this world—the "Reparo Charm."
Logically, this was just a first-year mending charm used to repair broken objects. But in this current Apocalypse environment, its strategic significance was simply immeasurable.
In this world, tools and weapons wear out. Axe blades dull, firearms jam, and crowbars can snap at critical moments. Possessing the "Reparo Charm" was almost equivalent to having infinite logistical support.
His quality of survival would undergo a qualitative change because of it.
A damaged car, which is scrap metal in others' eyes, could instantly turn into an escape tool in his hands. A walkie-talkie broken at a critical moment could be repaired to re-establish the team's lifeline.
Not to mention, his box of magic textbooks, which could be considered rare editions, would also have insurance.
This ability could even be elevated to a tactical level.
If he were forced to abandon a hiding spot in the future, he could first destroy the key weapons or equipment there, leaving the enemy empty-handed, while he could return anytime to restore them.
Louis even had a vague impression that if this spell were used incorrectly on a human body, it seemed to cause a completely opposite and terrible effect?
Although he couldn't remember the specifics, if it could serve as an attack spell under specific conditions to cause even more damage to enemies, it would undoubtedly be another trump card.
Logically, such a survival-god-tier spell should be at the top of the priority list.
In fact, Louis had done exactly that. Almost immediately after learning Wingardium Leviosa, this was the first spell he tried.
But this basic magic that every first-year Wizard could master was the most difficult for Louis to learn. From his current feelings, the difficulty of this spell even exceeded "Episkey."
If he hadn't quickly learned "Scourgify" and "Aguamenti" after many failures at the time, he would have even suspected he was a magic idiot!
That said, he still had to learn it; after all, the "Reparo Charm" was just too practical at this stage.
Of course, these were just short-term goals.
In the long run, what he most wanted to learn and had a relative hope of learning was that life-saving defensive spell—Protego.
Louis flipped to the few lines introducing "Protego" in the practical magic compendium, looked at the blank space next to it that didn't even have an ink mark, and sighed silently.
If possible, he also wanted to learn the Muggle-Repelling Charm and the Undetectable Extension Charm at light speed, as these would be of huge help to his situation.
Unfortunately, the Undetectable Extension Charm wasn't even within the scope of Hogwarts' curriculum, and the Muggle-Repelling Charm was a high-difficulty spell for the N.E.W.T.s... "Sigh, I'd better pray I can master 'Petrificus Totalus' on my own first!"
He couldn't help but complain resentfully in his heart about the predecessor who left the notes, "I say, senior, one must have dreams! What's the point of only wanting to be a St. Mungo's doctor? Couldn't you develop yourself more comprehensively?"
"Being a healer doesn't stop you from moonlighting as an Auror, then going undercover with Lord Voldemort, and finally being sent back to Hogwarts as a Defense Against the Dark Arts Professor or something... Write more notes for me, dammit!"
"As for 'Protego'... that's an advanced spell you only encounter in the fifth year. There are no notes in the book, not even a diagram! It's truly a long road ahead!"