Sectumsempra

From what Jerry had learned while watching the movies, the somewhat edgy title "Half-Blood Prince" was one Snape had given himself while he was in school.

And this sixth-year Potions textbook contained a great many of Snape's insights into Potions.

Of course, most of those Potions insights would only be useful when brewing sixth-year potions. Even if he memorized them now, they would not be of much use—like formulas used in advanced mathematics. Even if he memorized them, it would be difficult to apply them flexibly to elementary-school addition, subtraction, multiplication, and division.

So, getting these sixth-year Potions notes did not actually offer Jerry much help with his current first-year Potions studies.

However, what he valued was not Snape's Potions insights. What he truly cared about were the several spells Snape had invented and recorded in this Half-Blood Prince notebook.

Especially the most famous one: Sectumsempra.

It was a spell Jerry currently regarded as extremely important.

It was not because of its power. Judging from how Harry had only seriously injured Little Malfoy with it in the movie, Sectumsempra's lethality was not particularly great.

After all, spells like the Binding Spell and Stunning Spell could directly control someone upon hitting them, while the Killing Curse meant certain death. Sectumsempra merely caused severe injuries.

Of course, perhaps Harry had not been proficient with it. If Snape used it, its killing power might have been greater.

But one should not forget that even a first- or second-year Little Wizard could freeze someone in place with Petrificus Totalus.

Yet even so, Jerry still valued Sectumsempra greatly.

Because this spell had one especially prominent advantage: it was invisible and undetectable when cast.

Normally, casting a spell sent out a highly conspicuous beam of magical light. The Killing Curse, for example, flew toward its target as a streak of green light.

Although getting hit meant certain death, if one reacted quickly enough and predicted accurately enough, there was still a chance of dodging it.

But Sectumsempra produced no magical light at all. Casting it was like releasing an invisible blade. Unless someone had a Shield Charm up in advance, it was difficult to detect.

This advantage might not have been especially obvious in the Wizarding World.

Although Wizards had fairly decent physical abilities, their speed and reaction times were not much different from those of ordinary humans. Thus, in many cases, they could not evade magical attacks purely through physical movement.

Firing magic with a wand worked on the same principle as firing bullets with a gun.

At the speed of magic and bullets, ordinary people simply could not dodge.

Even those who successfully dodged did not do so because they were faster than magic or bullets. They merely predicted the attack trajectory from the movement of the opponent's arm and dodged in advance.

Very few Wizards could do that, so instead of dodging, they chose to defend with magic—casting a Shield Charm or directly clashing spells.

But in the Marvel world, there were quite a few people with superhuman bodies who could dodge bullets.

If ordinary magic was fired at someone with sufficiently strong physical abilities, they could dodge it just like a bullet, making it difficult for his magic to harm them.

That was when Sectumsempra came in handy. It was invisible and undetectable when cast, allowing it to injure an opponent before they even knew what was happening.

This was also a spell he had planned to obtain from the very beginning.

However, he had been busy memorizing textbooks before and had not found the time. Now that he had basically finished memorizing all his textbooks, and happened to have Potions Class today, he took it while he was at it.

With the Half-Blood Prince's notebook in hand, Jerry first returned to the Slytherin Common Room and hid the book in his trunk before heading back to the Great Hall on the first floor for lunch.

There were no classes on Friday afternoon, so after lunch, he returned to the dormitory once more.

Little Malfoy and the other two were not in the dormitory. In fact, boys their age rarely wanted to stay in their dormitories during the day. Most of them were off exploring the castle.

After resting for a while and recovering the mental energy he had spent activating Refreshing Mind during Potions Class that morning, he spent the afternoon alone in the dormitory studying the several self-created spells Snape had recorded in the notebook.

The notebook recorded a total of six spells: Sectumsempra, Vulnera Sanentur, Levicorpus, Liberacorpus, Muffliato, and the Toe Nail Growth Curse.

After reading through and memorizing all six spells, Jerry finally learned that Sectumsempra was not merely invisible and undetectable—it also possessed a curse-like property.

Any area cut by Sectumsempra would be cursed and unable to heal. Ordinary Healing Charms, potions, and even Muggle medical methods would not work.

Unless one used its corresponding counterspell—the Vulnera Sanentur Snape had invented.

Only then did Jerry realize that not all spells could be broken with the universal Counter-Curse, Finite Incantatem.

Many special spells required knowledge of the corresponding counterspell in order to remove their magical effects.

For example, if someone was suspended in midair by Levicorpus, they had to use Liberacorpus to release it, or wait for the spell's effect to fade on its own.

Under the effects of Refreshing Mind, Jerry's brain raced at high speed.

However, he did not know whether the spells Snape had invented were simply too advanced or whether his current Magical Theory and knowledge base were insufficient.

He spent an entire afternoon on them, yet failed to learn even a single spell.

When he had learned those first-year spells before, it had not been nearly this difficult.

Looks like I still need to go to the library!

Relying solely on first-year textbooks and what the teachers covered in class made it somewhat difficult to quickly learn spells on the level of Sectumsempra.

So he needed to learn from Hermione and spend more time reading related magic books in the library, accumulating additional magical knowledge to improve his magical ability.

Checking the time, he saw that it was already past six.

With his mind feeling sluggish, Jerry left the Slytherin Common Room and headed to the Great Hall for dinner.

After dinner, instead of chatting with the young Slytherins in the Slytherin Common Room, he went straight to bed to recover from the aftereffects of activating Refreshing Mind that afternoon.

It was impossible for Jerry to spend large amounts of time socializing.

His time was so precious, and he was using up Little Red Stars every day. Naturally, he had to spend it studying magic properly and increasing his strength.

And in Slytherin, as long as you were outstanding enough, as long as you could win plenty of honor for Slytherin, you would be Slytherin's coolest guy.

Whether or not one socialized was not that important.

Besides, as the future idol of all Little Wizards, it was necessary to maintain some distance from his fans and preserve a little mystery.

At eleven that night,

after all the Slytherin Little Wizards had fallen asleep, Jerry, now well-rested, got up and took his magic books to the common room. He activated Mind Refresh once again and entered study mode.