Transmigrating into Harry Potter, he gains a system that allows him to grow stronger through learning. While young wizards are still struggling with the Levitation Charm, Rock has already mastered the entire Standard Spellbook. Hermione: "His notes are more complete than Mrs. Pince's!" The Weasley twins: "Great Rock! We call you the strongest!" Snape: "Potter! If your potions were even a tenth as good as his..." [Flicker] is maxed out to the Law level, a single [Radiant] Holy Light will crush any dissent. [Levitation] is maxed out to the Myth level, a wave of the hand [Universal Pull] will hold the stars in his palm. When Voldemort brandishes the Elder Wand, announcing his 'Return of the Dead', Rock looks at the densely packed, dazzlingly bright max-level skill panel and silently pulls out the wand he's swung countless times. "Tom, have you ever heard of a spell that falls from the sky... Expelliarmus?"...

(The main text has been completed, and the movie-watching extra is being written)

Please don't mind this weird introduction.

After Bai'e and the pioneers offered the "Negative World" fire at the center of the Creation Vortex, his vision went black. When he woke up again, he found that he and his deceased Golden People companions had traveled to a strange world and shrunk to the size of a 10-year-old child!

As for why, just assume it was Aha who did it.

Dumbledore: Savior? Interesting.

Wan Die: Did I say to annihilate Wan Bang Nier Doron? HKS!

Na Ke Xia: Magic↗↘Skills↘!

Bai'e: Harry, why do birds fly?

Harry: ?

Voldemort: Don't come over here!

Xiadie: (smiles slightly)