But this isn't very practical in real life.
Because he didn't have an "Instance Finder" to randomly arrange instances, and Phantom Demons couldn't infinitely respawn like the bosses in the instances. So he could only feed them corresponding rare materials to level up the Phantom Demon—which required a huge cost, and collecting materials also took time and energy.
But if he had the "Shepherd's Nurturing" skill, he could use himself as fodder, sacrificing to the Phantom Demon.
Aiwass's oath was "I will not use the lives or corpses of my own kind as ritual materials or offerings," and he certainly didn't fall under that category.
After all, "self-sacrifice" was a standard ability for Demon Scholars. Moreover, it wouldn't prevent advancement to become a Great Sin Scholar.
Though "Shepherds" would become emaciated and scarred due to this flesh nurturing.
But Aiwass had the most orthodox Priestly heritage. Among the four Sacred Arts prepared over hundreds of years through meticulous selection by the church, the "Rite of Fire" could enable Aiwass to quickly recover lost life and heal his own bodily injuries.
—No need to use others as sacrifices.
It's enough to let the Great Beasts slowly feed on my own flesh.
Only, this cycle of spiritual flesh, feeding off the masses and perpetual movement, was unachievable for him.
He could grant others the power of the Phantom Demon and use his own flesh to feed it, but he couldn't feed humans he nurtured to the Phantom Demon in return—because that would involve sacrificing his own kind and would taint his soul.
At this moment, Aiwass also finally understood why this black-leather book reacted when it got close to Yulia.
Because it sensed the malnourished Phantom Demon that had been suppressed inside Yulia for a long time.
The original tome itself also had a faint spiritual awareness.
Incubating a Phantom Demon Egg was the simplest way to obtain a weak, juvenile Phantom Demon.
Within the illusions of that black-leather book, Aiwass saw that a "Shepherd" at mid-development acquired a multitude of juvenile Phantom Demons through this method:
The children, used as Phantom Demon Eggs, were gathered from all over the world by his legion. After long-term feeding with soups prepared using his blood, the Phantom Demons inside them grew rapidly, ultimately causing the "eggs" to crack and hatching out the Phantom Demons.
"...Anyway, first just destroy the book.
Aiwass muttered to himself.
Whether his foster father would become the ultimate boss or not, he couldn't let him see this book. Not to mention the trouble if his older brother or Yulia saw it. After all, the knowledge inside had already burrowed into Aiwass's brain; he couldn't forget it even if he wanted to.
From the moment he got the book, whether he used it or not, he would be suspected of having used it by those who knew.
So there was no point in being reserved. Not only would he use it, but he would use it thoroughly!
Just right, now there was a chance to try the soothing effect of the "Shepherd's Nurturing" on the Phantom Demons...
Thinking this, Aiwass stood up from his wheelchair.
The moment his feet touched the ground firmly and connected with the earth, the Shadow Demon lying dormant in his shadow was roused.
His shadow spread out like ink diffusing across paper in an instant.
A thick voice with echo arose in Aiwass's mind, filled with a dangerous feeling.
[You summon me... for what purpose?]
Aiwass said softly, tossing the "Nurturing Secret Sequel" into the bubbling shadow.
But it wasn't dissolved.
The Shadow Demon showed clear discontent.
[Heh, you can't always treat me like a trash can, master. Not everything can be thrown into me... I crave fresh flesh, sacred souls, is...]
Aiwass drew his pure silver dagger from the table as the Shadow Demon was expressing discontent.
It was a Ritual Dagger, excessively sharp but lacking in resilience.
Aiwass smeared the dagger with essential oils infused with cinnamon essence and rosemary, into which he had injected a bit of Light Attribute Mana and Dark Attribute Mana respectively.
Then, he passed it gently over a candle flame, and a deep, dim light emerged from the dagger.
Aiwass extended his right hand and took a deep breath.
Then, he clenched it fiercely until the blade cut through the flesh and lodged into the bone.
"Then take it, my blood, my bone, my flesh..."
Enduring the intense pain, he murmured in his heart:
[Feast in silence, my lamb...]
[This is the Holy Communion, this is mercy]
The Mana Pool within Aiwass suddenly loosened—the little remaining tri-colored Mana randomly infused into his blood, like water surging out uncontrollably from an unplugged bathtub.
He imagined that the blood flowing from his wound was not red but golden honey and white milk. He lowered his eyes and looked at the Shadow Demon with a compassionate and mournful gaze.
Aiwass strove to keep his heart free from any fear, greed, pain, and hatred, filled only with pure goodness and love.
As if what lay before him was not a cunning and deadly Demon but a starving street child begging for food.
It was pure, equable, supreme benevolence.
—Voluntary sacrifice carried a sanctity. Just as when Aiwass volunteered himself as an offering, he could summon an Upper-Level Demon.
And now, his willingly offered blood, transformed through the proper ritual, became an exceedingly sweet and delectable offering, potent enough to addict a Phantom Demon—