Trolls aren't native to Britain; they're originally from a place called Scandinavia, where they're also known as man-eaters. They don't have a fixed diet; any living thing can become their next meal, and that includes humans. To ordinary people in the Middle Ages, they were an incredibly dangerous creature.
Trolls are unbelievably strong, and their tough, coarse hide gives them a massive resistance to physical attacks. They can tear apart a small squadron of light knights with ease. Luckily, they're also dimwitted, with all that brute strength but no idea how to use it. Sometimes, all it takes is a simple Levitation Charm to take one down.
But that's not a hard and fast rule. If a Levitation Charm doesn't knock a troll out, the first thing you should do is... run. At close range, a wizard facing a troll is a dead wizard.
"That's the end of it," the Prefect said, pinching his nose and surveying his handiwork. The troll was bound up like a mummy with vines from a Transfiguration spell.
Aside from overwhelming power, most magical duels are about skill and technique. The Prefect, even though he was facing a troll for the first time and didn't know its weaknesses, managed to restrain it with just a few spells.
"Hurry, go tell the professors that we Slytherins have captured the troll." The Prefect clapped his hands and started giving orders to the younger students again.
Just as it seemed the crisis was over, Dudley's brows furrowed slightly. His nose was sensitive to smells, and the foul stench in the air was getting even stronger. The ground was still trembling...
The moment the Prefect turned his back, another head slowly peeked around the corner. Its pumpkin-sized eyes were fixed on the back of the Prefect's head. Another troll! And this one was even bigger than the last one, practically touching the ceiling of the Hogwarts corridor.
"What's wrong?" Seeing the terrified young wizards pointing behind him, the Prefect instinctively spun around. He found himself face to face with a massive head barely five feet above his own, with a pair of yellow eyes staring at him. He only had time to cast a reflexive Shield Charm before the troll knocked him aside like a Quidditch bat.
This troll was clearly much smarter than the last one; at the very least, it knew who the biggest threat was. Not all trolls are mindless brutes. Some are intelligent exceptions; they even have their own language, which a high-ranking Ministry official happens to speak. With a little training, these smart trolls can become perfectly good security guards.
The new troll let out a meaningless roar, but with his ability to understand magical creatures, Dudley could just about grasp the meaning of it: "Hungry... want to eat." And what was there to eat? Why, the little wizards cowering at its feet, of course. The Slytherin students, having been scared twice in a row, were now weak-kneed. They couldn't even stand up, let alone run.
The new troll opened its mouth, revealing a set of yellowed, rotten teeth, and greedily sized up the terrified students. Its eyes were filled with nothing but hunger. Dudley could see Pansy's slightly Poodle-like, delicate face filled with despair and terror.
"For the love of biscuits and tea..."
Dudley grabbed Malfoy, who was sprawled out at his feet, and tossed him behind him to a safe distance. Even though Malfoy had been training with him for a while, he was still just a slightly fitter young wizard. Dudley walked over to the wall, curled his fingers, and with a powerful grip, ripped a piece of the thousand-year-old castle wall right out.
Everyone was focused on the troll, so no one saw Dudley's little action. Good, no one would fine him for damaging historical artifacts. He clenched the rock and threw it with all his might at the troll's head.
"Flying Dust Stone (Physical)"
If his hand moved fast enough, it would just look like he cast a spell. This was a curse that an adult wizard would use in a duel; it creates a powerful explosion that shatters objects, much stronger than the Blasting Curse the Prefect used earlier. It's a high-level spell.
The head is a troll's weak spot. Don't be fooled by their small brains; it's still their most vulnerable area. If the Prefect had used a Blasting Curse on the first troll's head, he wouldn't have needed that whole chain of attacks; he could have killed it with a single spell. Before you're an unbeatable wizard, information and knowledge are your best weapons. That's why being well-read is essential for a spellcaster.
The moment the rock hit the troll's head, it exploded into a cloud of dust. You could see just how much force Dudley put into that throw. The troll was in a bad way; its head was dented, and blood was spraying everywhere. Dudley hadn't just hit its head; he had hit it right on the temple—the weakest part of the skull.
But that wasn't the end of it... "BOOM!"
The troll's head suddenly exploded, and the fiery red light from the blast illuminated the entire corridor. Explosive Potion! Dudley had added a volatile potion to the rock. When it came into contact with a certain amount of force, it created a massive explosion. It was one of the most dangerous potions Professor Snape had ever taught Dudley to make.
The potion had the physical power of dynamite, but it also carried a potent magical punch. It was perfect for taking down a tough, thick-skinned creature like a troll. The perfectly brewed potion completely blew off half the troll's head. The massive body crashed to the floor without even a groan.
Silence. Complete silence.
The Slytherin students remained frozen on the floor, staring blankly at Dudley. The whole scene had been so chaotic they had no idea what Dudley had truly done. All they saw was him using a single spell to make the troll's head explode. One spell! A headshot!
The fifth-year Prefect had used every trick he knew just to barely subdue a much smaller troll. And Dudley... he did it in one move. He didn't even flinch, as if he was used to this kind of thing.
Cold-blooded.
The young wizards instinctively added that detail to their mental image of him. Then they remembered the rumor about him using a single spell to make the Gryffindors fight each other... He was terrifying.
"He uses such powerful dark magic, such a terrible curse, and he's still saying he's not a dark wizard?!"
The main reason Dudley took such a direct approach was that he had no desire to get into close combat with the troll. In his mind, a troll's most powerful weapon wasn't its size or strength; it was the unbearable stench it gave off. The stink was a weapon in and of itself. No one wants to fight a pile of filth. Especially since Dudley's style was close-quarters combat.
There's a saying: "A mop covered in muck can take on Lu Bu himself." Trolls smell even worse than muck. That's why he chose that specific combination of attacks. It seemed to work pretty well, and now he had some ideas for how to fight wizards, too.
As the young wizards watched in shock, Dudley pulled out a bottle and walked towards the troll... The troll was already dead, so he figured he might as well collect some ingredients for his potions.
And this is what the Slytherin students saw... "This guy won't even leave a body alone!"
"No, wait, the great Mr. Dursley is experimenting with a new dark curse!"
And that's how the rumor started.
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