Out of solutions?
At least, judging from the current situation, it certainly seemed so.
Billions of Laḫmu, each individually strong enough to rival a first-rate Servant.
A black sea of mud that could curse and corrupt all life, burn all things to ash, and potentially engulf the entirety of Mesopotamia.
And then there was Kingu, Ushiwakamaru, and Okita Soji, along with Tiamat herself, transformed into the Beast of Original Sin.
How could humanity have any hope of resisting such power?
Even Rozen felt the crushing weight of it.
He could handle billions of Laḫmu.
With his current ability, if he unleashed everything, he could summon an army of equal size.
He could deal with the black sea of mud—so long as Tiamat herself did not intervene. With No. 1 maintaining her gem barrier, there was a way to keep the black sea from washing onto the shore, much less spilling across the land.
Kingu, Ushiwakamaru, and Okita, too, were not insurmountable—Rozen's own Servants were more than a match for them.
But everyone knew the truth. The real threat was Tiamat.
Tiamat could endlessly summon Laḫmu. No matter how many were destroyed, it was meaningless.
The black sea was merely another of Tiamat's authorities. As long as she willed it, it could spread across Mesopotamia without end.
Even Kingu was her child; Ushiwakamaru and Okita were merely corrupted by her authority. If she wished, she could always create new "Childrens" to replace them.
The only solution was to eliminate Tiamat herself.
In that sense, Tiamat and Rozen were alike—both capable of endlessly producing and summoning forces through vast reserves of mana.
No matter how many were slain, replacements could be summoned at any time, at the mere cost of some mana.
To defeat such opponents, one had no choice but to strike directly at the source. Otherwise, the only outcome was being exhausted to death.
And neither Rozen nor Tiamat could be called weak.
Rozen, even before gaining Cleansing, had stood unafraid before beings of Grand rank. With Cleansing, he had advanced even further—confident that he could now defeat even a Grand level enemies with ease.
But Tiamat was a Beast, transcending the Grand Servants. Only by gathering all seven Grands could she even be opposed.
Opposed, not defeated.
Even united, the seven Grands could only resist a Beast—the question of actually slaying one was another matter entirely.
Against such an enemy, Rozen could only speak honestly.
"Though I wouldn't say we have no recourse, I must admit—I don't have absolute certainty of victory."
So he confessed.
"If it comes to direct combat, I still have confidence in holding my ground against Tiamat."
After all, beyond Cleansing, Rozen had his trump card—High-Grade Mana.
Compressed to its extreme, only a step away from Foreign Mana, High-Grade Mana was a power Rozen believed capable of holding Tiamat at bay.
But when he beheld her true form, manifest as the colossal Beast of Original Sin, Rozen had realized something—
A fact so despairing it nearly crushed the heart.
"According to my Wise Eye, Tiamat emanates not only divine energy of unprecedented magnitude, but also a terrifying vitality—as though the primal seeds of all life in existence were gathered within her. Her spiritual aura is on par with, if not surpassing, my own."
"According to my Mind's Eye, her very existence is bound faintly yet inexorably to this land and to all humanity. Her structural being, her life-form, her spiritual foundation are utterly stable—without weakness, without flaw."
"If I am not mistaken, as the Goddess of Life, of Creation, of the Sea, of Origins—the progenitor of all life—Tiamat possesses no concept of 'death.'"
"In other words, no matter what happens, she cannot meet an end defined as 'death.'"
"She is, quite literally, an existence that 'cannot die.'"
"As the Mother of All Life that exists in this world, so long as life itself endures, her existence is assured. Death cannot touch her."
"Tiamat is both the God of Beginnings and the God of Ends."
"Unless every life in this world perishes, she will never acknowledge the laws of death."
Rozen's words drew sharp intakes of breath from everyone present.
"Unless all life is extinguished, she cannot die?"
Artoria [Alter] and Jeanne [Alter] were struck dumb with shock.
"You've got to be kidding."
Nobunaga and Hassan of Serenity stared in disbelief.
"So that's why she was banished to the Imaginary Numbers Space rather than slain..."
Ishtar could only click her tongue in astonishment.
"This… This can't be real..."
Siduri turned pale as a sheet.
Even Gilgamesh had no words.
At last, they understood what true despair meant.
It wasn't merely that the enemy was strong.
It was that the enemy could not be defeated at all.
Just as Rozen had said—Tiamat was, in the truest sense, an existence that could not die.
How was such a foe to be fought?
Not even Rozen could manage it.
He could withstand Tiamat—but he could never bring her down.
That was why he had chosen to retreat. Why else would he stand by as Tiamat strode toward the land?
"Could it be… even Miss Ryougi cannot kill the Goddess Tiamat?"
Mash couldn't help but voice the thought.
All eyes turned to Ryougi Shiki.
After a long silence, she answered bluntly.
"I haven't seen her yet, but if she really has no concept of death… then even my eyes won't be able to kill her."
The Mystic Eye of Death Perception could only intervene upon death.
If death did not exist, it could do nothing.
Rozen sighed inwardly.
(If only I had already completed the sublimation into Foreign Mana, then I would have a way.)
With it, he could wield the power of Miracle to open the gate to another world, banishing Tiamat forever.
Or, with true Foreign Mana, he could unleash the omniscience and omnipotence of Cleansing itself—to erase Tiamat's existence outright, or imitate Cain, demoting her from god to demon, from Beast to human, and thus making her killable.
But as he was now, with only High-Grade Mana, Rozen could not interfere with the very concept and existence of a world-ending disaster.
To counter a threat that endangered the world itself, only a power beyond the world could prevail.
Apart from Foreign Mana, there was no other power that could tamper with Tiamat.
Thus, even if Rozen could battle her for ten days and ten nights, until heaven and earth collapsed, he could never defeat her.
That was the truth.
His opponent was one who could rival, even surpass, him.
Against such a foe, humanity truly stood on the brink.
And yet—
"To say we have no solutions—that's not quite true."
Rozen suddenly spoke.
"Even if we can't slay Tiamat, we can seal her once more."
"With this."
Rozen revealed an object before everyone's eyes.