As for why the Four Symbols Seal, along with techniques like the Reanimation Jutsu and the Eight Gates, is considered a forbidden jutsu and placed on the Sealing Scroll...
The Four Symbols Seal itself is not inherently dangerous when used normally. However, if it is modified to extend into two other techniques, it becomes a sure path to death.
With slight adjustments, the Four Symbols Seal can transform into two different jutsu. One is the Dead Demon Consuming Seal, which summons the Shinigami to drag both the enemy's soul and the user's soul into the Shinigami's belly for sealing. The other is the Internal Four Symbols Seal, which sacrifices the user's own life, using their body's blood to seal all life within a hundred-meter radius into the afterlife.
In truth, the basic Four Symbols Seal and the double-layered Eight Trigrams Seal pose no inherent danger—they are simply very powerful sealing techniques.
"Thank you, Master!"
Credence could clearly feel that the Obscurus, which had always threatened to overtake his mind and reason, was now sealed within a part of his body, unable to interfere with him anymore.
He could continue to draw upon the Obscurus's vast magical power without worrying about losing control.
He was deeply grateful to Leo for all he had done. Over this period, he had been diligently studying magic, learning about the Obscurus, and understanding his own body and lifespan.
He felt that if there was anyone in this life worth risking everything for, it wasn't the parents who abandoned him and whom he had never met, but Leo—the person who had rescued him from darkness, taught him magic, and given him a new life.
"Continue your studies. You have great potential, and you'll certainly become a very powerful wizard in the future!"
Leo patted Credence on the shoulder, offering some encouragement before letting him continue his magical studies downstairs.
Though his time studying magic had been short, Credence's natural talent and the vast magical reserves of the Obscurus within him meant that the power of his spells was already on par with some ordinary Aurors.
With a bit more diligent study, his strength would undoubtedly be considered exceptional, making him a valuable ally.
"It's time to pay a visit to Dumbledore."
After instructing Bally to take care of Credence and Voldemort at home, Leo used Apparition to disappear from the spot.
With only five months available, he needed to learn as many powerful area-effect spells as possible from Dumbledore and Grindelwald during this time.
Because a wizard's magical bloodline doesn't run out of magic power, large-scale damaging spells, although not as lethal as single-target Killing Curses, are effective against large numbers of lesser enemies.
Previously, Dumbledore had wanted to meet him through Newt, but Leo had found an excuse to put it off.
At that time, he hadn't yet mastered Occlumency well enough and was worried that Dumbledore might see through his defenses.
However, after his time in the main world and the Naruto world, his Occlumency had reached a considerably advanced level. He no longer needed to worry about Dumbledore's Legilimency.
Moreover, his strength had significantly improved; even if Dumbledore saw through his defenses, he was confident he could handle the situation.
...
"Ding dong!"
Leo rang the doorbell of Newt's small house.
Moments later, a woman in a yellow long dress opened the door.
"Good morning, Mr. Fawley."
"Good morning, Ms. Bunty. Is Newt at home?" Leo asked with a smile as he stepped inside.
The woman, Bunty, was a witch Newt had hired specifically to help take care of the magical creatures.
In the wizarding world, apart from a few ancient pure-blood families, most households didn't have house-elves to serve them.
Moreover, not every wizard found a good job after graduating. Many ended up as housemaids, shop assistants, cleaners, or even struggled to afford their next meal.
It could be said that many wizards' living standards weren't as high as those of Muggles.
This situation primarily resulted from the Statute of Secrecy. Wizards couldn't perform magic in front of Muggles, and naturally couldn't use the convenience of magic to earn a living.
If wizards could use magic within Muggle society, even those doing poorly could make a substantial income with various magical skills, leading a relatively luxurious life.
Look at someone like Lupin, a powerful wizard who, due to the prejudice against werewolves, couldn't find suitable work in wizarding society and wore shabby clothes.
Without the Statute of Secrecy, he could have lived quite comfortably, even posing as a magician.
"Mr. Scamander is downstairs feeding the Kelpie," Bunty pointed towards the basement stairs.
Leo nodded and headed down the stairs to the basement.
In London, many homes have basements, or more accurately, cellars, typically used to store wine, non-perishable canned goods, toilet paper, and various odds and ends.
However, Newt's basement had clearly been modified with the Undetectable Extension Charm. The actual space was far more expansive than his suitcase—indeed, it was quite vast.
It wasn't just a simple one-story area of a few dozen square meters. It had multiple levels, including forest zones, snow areas, desert zones, and even lake regions.
Sometimes, Leo felt he was quite skilled in the Undetectable Extension Charm, but compared to Newt, his abilities seemed lacking.
Then again, he had focused most of his efforts on mastering powerful dark magic, whereas Newt had spent decades refining the Undetectable Extension Charm to provide a home for magical creatures.
Of course, Newt's actions technically violated Ministry of Magic laws, as personal property couldn't be enchanted with the Undetectable Extension Charm.
However, no Ministry official would bother checking up on it, and Newt was hardly a wizard who followed rules strictly.
Moreover, most wizards did similar things in private; as long as they weren't caught red-handed by an Auror, it wasn't a serious offense—just a fine and a warning.
Following the stairs down to the lake region, Leo soon saw Newt riding a Kelpie, emerging from the lake and quickly plunging back in.
A Kelpie is a magical creature capable of transforming into various forms, usually appearing as a horse with wide-leafed sedges for a mane.
They enjoy luring humans onto their backs and dragging them underwater to drown and devour them, making them quite a vicious magical creature.
However, since their mane can be used as a core for wands, they were heavily hunted by wizards. Nowadays, their numbers have become very scarce, and Newt is trying to help them.
The largest known Kelpie resides in Loch Ness in Scotland, famously known as the Loch Ness Monster.