“...Game select.”
The voice came from right beside Alkeides.
From among the Berserkers who had become corpses in that short time.
In the midst of that pile, one body Alkeides could not remember slaying moved its mouth and hands and rapidly performed magecraft.
A moment later... one of the arrows Alkeides had nocked burst, causing his now-grotesque frame to stagger for an instant.
Impossible.
Alkeides immediately realized what had been done to him.
The current of magical energy necessary to activate the Stymphalian Birds, part of his Noble Phantasm, King’s Order, had been tampered with and made to short-circuit.
That, however, was only the beginning of the spell.
“Ngh...!”
Just as he tried to regain his footing, he was struck by another wild burst of magical energy. Alkeides was not a mage, but as his body was itself a mass of magical energy, every vein and nerve in it could be called a Magic Circuit.
All of them had become fuses and were setting off surges of uncontrolled magical energy one after another in a chain reaction.
Magical energy burst in his lean, steely arms.
Magical energy burst in the toes of his feet, so well-honed that they sometimes became blades.
Magical energy burst in the veins that ran throughout his body, deep and strong as the roots of the world tree.
Magical energy burst in his beautifully woven nerves.
Magical energy burst in each of his alveoli before he even had a chance to breathe.
Magical energy burst behind his eyeballs, hidden by his cloth.
Magical energy burst in a part of his brain stem.
It burst, and burst, and burst...
The interval between bursts of magical energy grew shorter and shorter until at last he felt a massive explosion of magical energy near his heart.
He could not distinguish the pain from the heat of it.
Half of the wings on his back and the horns on his head snapped off. There was even an explosion of magical energy in the hand that held his bow, tearing off several of his thick talons.
The magical energy ran out of control inside his body as well, shredding parts of his organs.
But his Spirit Origin, once renowned as a great hero, was to be feared.
“...No!”
With a shout of effort, he stamped his foot down onto the street and poured his rampaging magical energy into the earth.
A moment later, the asphalt lifted in patches all along the street, which ran for several hundred meters, and ruptured pipes shot fountains of earth and water into the air in unison.
Many Heroic Spirits might have burst entirely at that point, but he had held his body together by the force of his sheer physical strength.
Even so, the resulting damage was extraordinary.
The backlash had torn up the street around him and a number of cars that had been parked along it were overturned and half scrapped.
Alkeides’ insides, however, had suffered far greater damage than the cars.
It would ordinarily be inconceivable for a single mage to inflict such damage on a Heroic Spirit.
Alkeides’ Spirit Origin, with its extraordinarily powerful Anti-Magic, was impervious to modern magecraft.
Meaning... it had backfired.
There was one part of his Spirit Origin whose Anti-Magic was weak.
It was also a part of Berserker, meaning that a path of magical energy had linked it to the young man who had until recently been its Master.
The mage had introduced a spell that disturbed the flow of his magical energy through the power of the Noble Phantasm he had stolen from Berserker—the part of him that had transformed into a demon, a kind of phantasmal.
Even so, it was no easy feat.
Unless the mage had a complete grasp of the complex flow of his magical energy in this condition, it would be impossible.
Meaning that he had accomplished that.
“I had to get this close for it to work,” the mage who had been hiding among the crowd of
Berserkers said, revealing a relieved smile.
The Berserker corpses around him began to vanish. At the same time, the corpse of the mage Alkeides had just shot through disappeared completely.
It had been Berserker in the form of the mage Flat Escardos.
Circumstance piled on circumstance dulled Alkeides’ mind’s eye for an instant.
And that momentary unbalance... created a fatal opening.

Fate/Strange Fake: Volume 5, Chapter 15 ("Gold & Lions II")