Back then, to devour the Soul Fragment that was Tom Riddle, Voldemort designed an unstable set of Bloodline Magic that drew on the ideas of Alchemy.
Alchemy often pursued harmony and compatibility, but Voldemort's Bloodline Magic took a different approach, deliberately destroying that harmony.
"The blood of a pregnant Unicorn" and "the flesh and blood of a venomous snake, and a Runespoor Egg" were tangible, while "memory" was something illusory and intangible. Fusing the three would naturally lead to disharmony and conflict.
Besides that, Alchemy also valued balance and flow. "The blood of a pregnant Unicorn" and "the flesh and blood of a venomous snake, and a Runespoor Egg" were tangible, and could flow between each other;
while the "illusory" Memory Thread from Voldemort also needed to flow with the "illusory" Tom Riddle.
With the help of these two Alchemical principles, Voldemort ultimately completed the devouring, allowing the Soul Fragment that was Tom Riddle to return to the main body.
It was only after a round of research that Vizet had untangled the secrets and subtleties within.
It was precisely because of this that, by combining the Ritual Magic Array with the "fear" potion inside the helmet and the silverware, he could judge that the test Dumbledore had set was actually based on Voldemort's Bloodline Magic.
After all, Dumbledore himself was extremely skilled in Alchemy. He could trace things back to their source and determine that that set of Bloodline Magic had drawn on Alchemy. For Dumbledore, realizing this should have been even easier.
"Since the Alchemy Magic Array in the classroom works on this principle..." Vizet murmured softly, "the 'illusory' 'fear' comes from the students entering the room..."
"Then it needs another 'illusory' part to 'flow'..." He raised his Wand and lightly waved it at the helmet in front