"I just remembered..." Vizet began drafting the fourth proposal. "I once translated a very ancient Runes rubbing, and it mentioned a certain idea."
"Before performing 'Ritual Magic,' you must keep the ultimate purpose of the 'Ritual Magic' firmly in mind, or something terrible will happen. It's not as simple as the Ritual Magic failing—you can become lost within the Ritual Magic itself."
Among the wand techniques Ollivander had taught him, similar matters had also been mentioned.
That was an era before wands had appeared, when even the Ollivander Family was still exploring Wand-making techniques;
While traveling abroad, the ancestors of the Ollivander Family had encountered an extremely strange Wizarding Family;
The adult members of that Wizarding Family all possessed a strip-shaped casting tool called "Castor";
Through some form of "Ritual Magic," that Wizarding Family could always give birth to pair after pair of same-sex twins, but when the twins grew to eleven years old, only one of them could survive;
The reason this happened was that when the twins turned eleven, that Wizarding Family would enter a valley and hold some secret "Ritual Magic";
And the final step before this "Ritual Magic" began was to send both twins into the "Ritual Magic";
Once one of the twins died, the other would use their corpse as a casting tool to discover the path out of the "Ritual Magic" and return to that Wizarding Family.
Relying on their experience, the ancestors of the Ollivander Family worked out the possible nature of this "Ritual Magic": the dead twin became part of the "Ritual Magic" and possessed some kind of magical property;
By relying on that magical property, the surviving twin could use the dead twin's corpse to successfully escape the valley where the "Ritual Magic" was located, then craft the corpse into "Castor."