Harry's position happened to be at the back of the crowd, and in the face of the sudden attack of the abyssal maw, Harry was a little stunned for a while.

The foul smell sprayed on his face, making Harry almost sick, and just as the despair spread all over his body, Ivan's voice suddenly rang in Harry's ears.

"There are many obstacles!"

Invisible barriers blocked the hideous head of the three-headed dog in midair, but in the next second, the barrier that Ivan maintained and constructed with his magic power was torn apart by another big mouth with fangs!

Fortunately, in just one second, Harry had already reacted in time and barely escaped.

Ron, on the other hand, shouted a quick run, and the whole person had already jumped to the door, and he pulled hard with both hands a few times, only to find that the door had been locked.

"Which bastard locked the door!" Ron said in despair.

Ivan, who temporarily restrained the three-headed dog with the stun spell and the petrification spell, couldn't help but roll his eyes, didn't you lock the door yourself?

Ron panicked, even suspecting that he might die here, but Hermione pushed him away and placed his wand on the door lock.

"Alaho Cave Open!"

Hermione struck the door opening spell and violently broke the door lock, and the group of five escaped as fast as they could, and then closed the door back in time before the three-headed dog Norway came out.

Boom.. Bang bang!

After leaving, listening to the faint sound of knocking on the door and roaring in the distance, the few people who escaped death breathed a sigh of relief, especially Ivan, who was inexplicably swept in.

When he was restraining the three-headed dog Norway before, Ivan found that his magic level was too low and had a limited effect, and the coma spell would affect the three-headed dog's actions at most, and he would not fall down at all.

If Hermione had opened any later, he might have had to get his bento, after all, in such a small space, there was not even a place to hide.

This also made Ivan deeply understand his weakness, and he might be easy to deal with a first-year wizard like Malfoy, but he didn't even have the ability to struggle in the face of real danger.

"That monster won't run out of the door, will it?" Ron glanced at the door behind him, and then complained.

"No, this should be a special door, otherwise it would have been broken a long time ago." Ivan explained.

"How could Professor Dumbledore keep such a monster in a castle?" Harry was also a little frightened, he had never thought that he would encounter such a terrifying thing at Hogwarts, and he was almost eaten by it!

Hermione reminded angrily.

"I think you should remember when we first entered the school, Dumbledore told us that this place should not be here, and if we hadn't broken the school rules and came out in the middle of the night today, we wouldn't have crashed into this place in a panic!"

Perhaps because she had just escaped death, Hermione's tone was much sharper than usual.

Harry and Ron knew that Hermione was about to start a tirade again, and Neville almost cried.

Who would have thought that after Hermione vented, she didn't mean to sue, but revealed the fact that she had seen a trapdoor under the three-headed dog before, and her guess that she suspected that the three-headed dog was guarding something.

However, before leaving, Hermione warned Harry and the others that whatever was down there had nothing to do with them, and this should be something for Professor Dumbledore to consider!

Hermione's attitude was a bit unpredictable for Harry and the others, but thankfully Hermione wouldn't have told Professor McGonagall about their violation of school rules tonight.

"I didn't expect Malfoy to be so insidious, he must have told Filch what happened to us in the trophy room!" Ron, who returned to the dormitory, was still a little angry, and threatened to beat Malfoy tomorrow.

"Ivan, I knew we should have listened to you." Harry was a little embarrassed, after all, Ivan had already mentioned this possibility to them in the afternoon.

"Forget it." Ivan waved his hand, indicating that he didn't care, after all, he hadn't expected Harry and Ron to resist the temptation to stay in the dormitory, and it was his bad luck to bump into him halfway this time.

"By the way, Ivan, why were you in the hallway just now?" Harry wondered.

"I'm not here to look for you." Ivan said casually, he can't say that he sneaked into the forbidden book area in the middle of the night to read books, right?

Harry and the others were suddenly even more ashamed, but before they could last a few minutes, they were thrown aside by a few people, and instead discussed the trapdoor guarded by the three-headed dog, guessing what was hidden inside... Eventually, Harry told him about the package he had taken out of Gringotts with Hagrid before school started.

Ivan wasn't involved, the challenge mission he had just activated was enough of a headache for him, and he had no interest in meddling in Dumbledore's layout again.

The only thing to be thankful for is that there is still some time before the troll-infested Halloween, and he still has some time to prepare.

.....

For the next week or two, Ivan worked hard to improve his strength, and the rest of the time spent frantically searching the library for books about trolls.

"A Detailed Explanation of Common Magical Creatures"..."A Guide to the Domestication of Dangerous Monsters"..."On the Possibility of Hybridization between Giants and Trolls"...

Even the book "Walking with the Trolls" was turned out by Ivan.

That's right, the author of this book is none other than Gilderoy Lockhart, who will be in charge of teaching Defense Against the Dark Arts class for Chino next semester.

Although Ivan knew that Lockhart was a liar who only forgot the curse, that didn't stop the authenticity and professionalism of the book's contents, which is why he was able to find it in the Hogwarts library.

Truth be told, Ivan didn't want to open Lockhart's trademark smile with white teeth on the cover.

But who makes the content of the first few books unreliable, "Detailed Explanation of Common Magical Creatures" only mentions that trolls have no medicinal value, and there is no place from the brain to the torso after entering the pot is delicious...

The description of trolls in The Domestication Guide to Dangerous Monsters is that wizards can often use more power to bring them to their knees.

Isn't this TM nonsense?

If he had the strength to defeat the trolls, what would he be doing here?

The book "On the Possibility of Hybridization between Giants and Trolls" used illustrated and illustrated academic methods to make Ivan call for spicy eyes.

On the contrary, in "Walking with Trolls", there is a detailed introduction to the habits and weaknesses of trolls in the form of biographical narratives.

For example, trolls usually don't have a high IQ, eat a lot and eat everything, so if you want to deal with it, placing a bait is a more correct choice, and there is a high probability that the troll will eat the bait.

The troll's small bean-like head and huge body make it less stable, and if you hit the troll's leg with a powerful spell, you might be able to break the balance and knock the troll down, allowing you to run a few more steps before being eaten...

Finally, the troll's head itself is also a weakness, much more fragile than the rest of its body, and if it is hit by gravity, it is likely to be directly unconscious.