Control Amnesia.
As the name suggested, it was magic that could manipulate an individual's memories.
It allowed the user to browse, erase, or even alter the target's memories, making it useful for gathering intelligence or creating false information. Among all surveillance magic, it ranked among the best, classified as 10th-Tier Magic.
However, this magic had a major drawback—it consumed an enormous amount of magical energy.
Another 10th-Tier Magic, Reality Slash, was also known for its extreme magical energy consumption, but Control Amnesia consumed even more. In the world of Overlord, even a max-level player like Ainz, who possessed an overwhelming amount of magical energy, would be drained within a short period after using this magic.
As a result, even Ainz rarely used it, as its cost-effectiveness was too low. If his goal was simply intelligence gathering, there were far more convenient surveillance magic options available.
Even Riezel, who possessed 'Spirit Healing' at the highest rank, which allowed him to regenerate his depleted mind rapidly, might find himself experiencing magical energy depletion and mind exhaustion for the first time if he used this magic since the recovery speed simply couldn't keep up with the consumption rate.
Nonetheless, compared to others, Riezel would definitely last longer, so to investigate the origins of these black-robed figures, he decided to use this magic to peer into their memories.
Riezel's consciousness, along with the magic, eventually delved deep into the memories of one of the black-robed figures.
Soon, however, Riezel was surprised to find that this black-robed figure's memories were surprisingly few, and in terms of quantity, they were equivalent to only a few years' worth.
'What... this guy only has memories from the past few years?'
Riezel frowned at this revelation but still began browsing through the memories, flipping through them all.
If it were anyone else, Riezel wouldn't dare be so rough since memory was, after all, a very fragile domain, and interfering with it carelessly could easily have an impact on the memory's owner, potentially causing damage to their cognitive functions. If he wasn't careful, he could end up damaging the person's brain domain, leading to errors in their memory or even their perception.
However, since the target was someone who had tried to kill him and even attacked those close to him, Riezel didn't care what happened to the black-robed figure. For this reason, to save time and magical energy, he roughly forced open the black-robed figure's memories, not caring about the consequences at all.
Thanks to this, Riezel successfully accessed the memories of the black-robed figure and learned that the first memory he accessed was the day this black-robed figure was born.
At that time, the black-robed figure seemed to be lying in a pitch-black place, and before even opening his eyes, two voices rang in his ears.
"It looks like this time was a success."
"Yeah, after taking out so many people, we finally succeeded with one."
"Still, this efficiency isn't exactly high. Can't we think of a way to improve the success rate?"
"Be grateful. You know, with the quality of this magic doll, one can already tie up a Sword Saint, so the fact that we can mass-produce them like this is nothing short of a miracle. If those big countries find out about this, they'd be willing to pay any price to get their hands on this technology."
"...Maybe it's fate that this technology ended up in our hands?"
"I just wanted to use modern magic technology to reproduce this technology, but sadly, after so long, I still haven't seen a glimmer of hope."
"If even you can't reproduce this technology, then I guess no one else in the world can do it, huh?"
"No... there's one person who can."
"You mean...?"
"Hmph..."
"Alright, fine. Anyway, you're the only one among us who can use this technology to create magic dolls right now. We'll gather the materials for you, so all you need to do is focus on producing the dolls."
"I don't care. As long as I can decipher the precious knowledge left behind by the ancient magic civilization, I'll do whatever it takes."
"I know. It's because of that that we believe in you."
As soon as these words dropped, the conversation ended.
Later on, perhaps due to falling into a coma, the memory of the black-robed figure was blank for a long time, and when he regained consciousness, he had already arrived in an unknown place, where he met many of his own kind.
From then on, the dull life of these figures without hearts—or rather, magic dolls, began.
Like real dolls, not only did they not need food or sleep, but they also didn't even feel tired. Additionally, their minds lacked the clutter of human thoughts and the common sense of human society, leaving only an instinct for action that seemed inherent, which drove them to follow someone's orders and do things according to those orders.
Who this person was, these magic dolls didn't know since they had never even seen their face, but if the person gave an order, the contents of that order would naturally appear in their minds. When there were no orders, they hid in deep mountains, forests, or even buried themselves in the ground to sleep.
Meanwhile, if a mission required them to gather certain intelligence, that information naturally surfaced in their minds.
Like this time, as these magic dolls received orders to eliminate Riezel, information about his appearance, strength, and location flooded into their minds, prompting them to act immediately.
During this mission, they received two instructions.
One was to take those strange chains from a fellow magic doll, while the other was to go to a certain location, meet with the Holy Beast there, enter its body, and wait for the right moment.
Riezel saw the fellow magic doll in question, whose face was as stiff as a corpse, just like the other dolls, with no other distinguishing features. He also saw the so-called Holy Beast, but all he saw was a huge black shadow suddenly appearing beneath these magic dolls before they appeared in this cave.
And just like that, the memory ended there.
"..."
Riezel silently moved his hand away from the head of the magic doll in front of him.
At this moment, the magic doll had already fallen into a dazed state, like a vegetable, proving that Riezel's brutal memory-reading magic had, in the end, still affected it.
Nevertheless, Riezel didn't pay attention to it.
'Magic dolls...'
As expected, these strange figures without hearts weren't humans, but dolls made for some purpose.
Moreover, from the conversation between the two voices he had heard when this magic doll was first created, it was clear that the technology used to make these magic dolls had been passed down from an ancient magical civilization. After this technology fell into the hands of certain people, they began to use it to create these magic dolls on a large scale.
However, making these magic dolls wasn't something that could be done casually.
First of all, the one capable of using the technology from the ancient magic civilization to make the magic dolls was, even among the masterminds behind the scenes, just one person.
Secondly, the process of creating the magic dolls wasn't always successful.
Finally, making these magic dolls required a lot of people to be sacrificed.
'Now, the clues are clear.'
Riezel now understood that the reason why so many people had disappeared in Mavros Territory was that those who possessed the technology of making these magic dolls needed living people as materials, either by working with the local lords or by completing commissions through other channels to acquire a large number of living people.
All of this was to make magic dolls, dolls that could even rival a Sword Saint's combat power.
As Riezel made this deduction, he proceeded to read the memories of the other three magic dolls, and ultimately, his suspicions were confirmed.
However, the problem was—
'Who are those people?'
'What are they trying to do by making so many powerful ancient magic dolls?'
'They said I would get in their way, meaning they don't want me involved in this, right?'
Riezel couldn't help but feel the situation was getting intriguing.
'Too bad I couldn't get any information about that cold, sinister energy. Seriously, these magic dolls' memories didn't have a single clue about it...'
In these magic dolls' memories, they only knew that the cold, sinister energy was inherent, capable of many uses. It could, just like when it targeted Lizbeth earlier, paralyze someone, making them unable to move, and could also have various effects on the human body. Once touched by this energy, even a Sword Saint would be entangled by it, severely weakened.
Riezel's earlier feeling had been right.
A regular Level 7 could easily be killed by these magic dolls on their first encounter. If they didn't understand the cold energy and got hit by it, they would likely be done for.
Moreover, the daggers that looked like sharp claws and the chains filled with cold, sinister energy that these magic dolls used were called holy relics in their memories—especially the chains, which seemed to be higher-tier weapons among these so-called holy relics.
At first, these magic dolls didn't have them, and the rest probably didn't either. It wasn't until these dolls took on the mission to eliminate Riezel that they received these holy relics as aid from the mastermind behind the scenes.
'Are these so-called holy relics also made with the technology left behind by the ancient magic civilization?'
As Riezel thought this, he believed it was the only explanation.
It was only natural.
If weapons that could make a Sword Saint like him instinctively feel wary were created in the modern magic civilization, then this technology would be well-known all over the Akasha Continent already.
"Holy Beast, huh..."
Riezel muttered and lifted his eyes to look toward the cave walls.
Not long after, Riezel flew toward the other side of the cave, leaving behind only the remains of the magic dolls and the numerous beetle monster corpses around, proof of the unrest that had once taken place here.