Goblet of Fire Registration Ceremony

Looking at Fred and George's long grizzled beards, Luna asked curiously, "You already passed the selection test, so how did the age restriction still stop you?"

Wizet looked down at the ground, where two scraps of parchment lay scattered. They bore Fred and George's names, along with the school name "Hogwarts."

Besides that, nearly half a bottle of green potion lay on the floor.

There were many kinds of green potions, but combined with the parchment used for registration and Fred and George's grizzled beards, it was easy to determine that this was a bottle of Ageing Potion.

The key ingredients of an Ageing Potion were aged red wine and tortoise shell. Explained in terms of "imprints," the potion needed to acquire the "years" of the aged red wine and the "experience" of the tortoise.

The "years" and "experience" had to correspond to each other. For instance, if eight-year-aged red wine was used, it had to be paired with tortoise shell from a tortoise around eight years old.

It also required bat tongues, caterpillar pupae, and essence of Dittany.

Bats possessed the unique ability of "echolocation," so bat tongues could be used for "regression," ensuring that once the potion wore off, the drinker could return to their proper age.

Caterpillar pupae were similar to the pupae of Death's-head Hawkmoths. The "transformation and rebirth" contained within them could help the bat tongues "regress" the drinker's age.

After returning to their original age, the healing effects of essence of Dittany could repair the damage caused by altering one's age.

In truth, Fred and George did have a chance of succeeding with the Ageing Potion.

However, they needed to undergo "ageing" in every aspect. Once their bodies had aged, their souls needed to age as well.

At the very least, they would need