Taking advantage of the chaos in the Great Hall, Chen Yu, seeing no one paying attention to him, decisively ran out of the Great Hall, then used the Serpent Spell to become invisible, and headed straight for the fourth floor.

The Charms Class classroom was on the fourth floor, and Neville had said that Hermione had been crying in the lavatory after class, so it was highly likely she was in the girls' lavatory on the fourth floor.

Chen Yu couldn't guarantee that Hermione would be safe this time, as she was in the original story.

After all, Hogwarts had an extra person, himself, and with the various butterfly effects he had caused, whether the story would still follow the original plot was a question.

As soon as Chen Yu reached the third floor, he smelled a foul odor.

It was a mixture of stinky socks and lavatory smell, so strong it made one's eyes water.

The stench was so overwhelming it almost made Chen Yu throw up his dinner.

Chen Yu immediately cast a Bubblehead Charm on himself with his wand, which helped him recover.

He saw a behemoth, three to four meters tall, lumbering slowly at the end of the corridor.

It had a gray body like granite, short legs, large feet, and long arms. It held a thick wooden club in its hand and made grunting, snorting sounds from its mouth.

Compared to its massive body, its head seemed exceptionally small, a bald little head incongruously attached to its huge frame.

Trolls are unintelligent humanoid monsters that live in mountains, forests, and by rivers.

They are categorized as Mountain Trolls, Forest Trolls, and River Trolls.

They are incredibly strong, brutal, utterly stupid, and carnivorous.

They don't care whether their prey is human or other animals.

The Troll before him was a dangerous Mountain Troll.

However, they usually live in the wild, and its pitiful brain capacity couldn't comprehend the complex corridor environment inside Hogwarts.

At this moment, it seemed confused, as if it didn't understand why it was here, and wandered aimlessly in the corridor on the third floor.

This was a good opportunity!

Before this Troll reached the fourth floor, he should quickly subdue it, so he wouldn't have to worry about Hermione being in danger.

Chen Yu pointed his wand at the Troll and immediately chanted the Full Body-Bind Curse: "Petrificus Totalus!"

The Troll's arms slapped against its sides, its legs snapped to attention, and it stood perfectly straight.

Its body instantly became rigid, looking like a stiff wooden plank.

Chen Yu thought his spell had worked and was about to rejoice when he saw the Troll immediately break free from the Full Body-Bind Curse's effects, clutching its wooden club and warily scanning its surroundings.

Damn it!

This Troll had too much magical resistance, truly living up to its XXXX-level magical creature status; its magic resistance was second only to an Acromantula.

Use the Killing Curse?

No! The Hogwarts professors were all nearby and could arrive at any moment, and Dumbledore's eyes were everywhere in the school; if they found out, it would be impossible to explain.

Use Sectumsempra?

That wouldn't work either!

Snape was the inventor of Sectumsempra, so he would definitely recognize the wounds caused by Sectumsempra.

How did Ron deal with the Troll in the lavatory again?

Right, use the Levitation Charm!

Use its own giant club to smash its head.

The Troll's brain was its weakness; its head couldn't withstand a violent impact.

The book "Traveling with Trolls" also stated that the Troll's weakness was its head.

Although Lockhart's books plagiarized others' experiences, most of the knowledge points in them were true.

The Troll was indeed an unintelligent creature; after looking around and finding no one, it scratched its head and resumed its aimless wandering.

This time, Chen Yu directly used the Disarming Charm on the nearby Troll: "Expelliarmus!"

A red light, without warning, directly knocked the giant club from the Troll's hand.

Immediately following was Accio: "Accio Club!"

Accio is actually a type of summoning spell; it can not only make objects fly towards you but also make them fly away. Its full spell name is "Accio and Repello."

Chen Yu chanted Accio again: "Club Repello!"

The giant wooden club, flying towards Chen Yu, flew past him at an even faster speed the moment it reached his front.

After arcing gracefully through the air, it directly hit the Troll's head.

The Troll, who was bewilderedly staring at its empty right hand, wondering why its club had suddenly left it, received this heavy blow completely unprepared.

The Troll, its head violently impacted, immediately fell unconscious.

Just as Chen Yu thought the incident was resolved and was about to breathe a sigh of relief, he was shocked to discover another Troll, carrying a giant wooden club, slowly emerging from the corridor corner.

This Troll was uglier and appeared more robust than the one he had just dealt with.

Bloody hell, how many Trolls did Quirrell let in?!

Chen Yu had no time to be surprised and wanted to use the same trick again.

He cast a Disarming Charm at the new Troll.

But this Troll, seeing its fallen companion, was already very wary; his Disarming Charm barely scratched the Troll, and the giant club in its hand didn't fly out.

It seemed this new Troll was considerably smarter than the previous one.

Although it couldn't see Chen Yu in his invisible state, it still charged forward, wildly swinging the giant club in its hand, heading straight for the source of the spell.

Chen Yu immediately used Bukū-jutsu to hide in mid-air.

The Troll, realizing it had missed, still warily watched its surroundings.

Chen Yu quickly used Accio to summon the first Troll's club, then once again used it to smash the second Troll's head.

Unfortunately, the prepared Troll directly blocked the incoming club with the club in its hand and then shattered it in frustration.

Chen Yu had no choice but to temporarily retreat, preparing to fly in the opposite direction of the Troll.

When he saw the shattered pieces of the club and the Transfiguration Charm, which he had already leveled up to LV2 on the system page, a thought surged into Chen Yu's mind.

He immediately went offline and quickly searched for firearm structures on his phone.

Wood becomes iron, glue becomes solder, three small prison meals a day.

Change the material, and you're in jail for life.

Chen Yu repeatedly watched a video of a certain YouTuber making firearms out of wood.

Feeling that he had memorized all the mechanisms of a handgun, he immediately went back online.

A handgun is mainly composed of a barrel, grip frame, firing mechanism, launching mechanism, and slide.

The gun body extensively uses new materials such as hard aluminum alloy and engineering plastics.

He summoned a piece of wood and then used Transfiguration to turn it into a wooden revolver.

Now, the important part.

"Vera Verto!"

He cast the Transfiguration Charm again, and the wooden handgun in his hand slowly transformed into a silver-gray texture.

With Chen Yu's current Transfiguration level, directly turning a block of wood into a real handgun was quite strenuous, but transforming the wood into a wooden gun and then into an alloy one felt much easier.

The handgun body was complete; next were the bullets.

A bullet consists of four parts: the projectile, the casing, the propellant, and the primer.

He again summoned a smaller piece of wood, then used the same method to transform the wood into a wooden bullet, and then into a real bullet.

He loaded the bullet into the chamber.

Holding the handgun with both hands, he aimed the sight at the Troll, which was still warily scanning its surroundings.

He pulled the trigger, and with a bang, the bullet surged from the barrel, shooting into the Troll's forehead at an extremely high speed.

The Troll's entire body had decent magical and physical resistance, but its head was its only weakness.

After the gunshot, a hole appeared in the Troll's brow, its eyes lost their ferocity and became vacant, and it swayed twice before collapsing to the ground.

Looking at the fallen Troll, Chen Yu, mimicking a cowboy in a movie, blew away the smoke from the muzzle and said to the Troll, "Times have changed!"