In Mushoku Tensei with an A.I. Chip

Ghislaine was shocked that there was a magic item that could block the all-out attack from a Sword King's Longsword of Light. But any such magic item had to have a limit, or else it would be magicians, and not swordsmen, who dominated the battlefield. 

She pulled back her sword and swung back for a second attack. But before her second swing could make contact with the barrier, her Demon Eye caught a surge of mana exploding in her direction.

"Latent Fireball." Luke's cold voice was the only other warning Ghislaine received before an intense heat swept through her. 

A wave of black fire exploded outwards from Luke's hand that was down by his side. The giant plume of black fire covered half the arena, and emitted a terrible heat that could be felt even from the Boreas guests who were watching from a healthy distance away. 

"What…?" Sauros felt his jaw drop from the sight. Thankfully for his aged heart, his prized Sword King bodyguard could be seen leaping out of the surge of black fire. 

Ghislaine landed on her two feet, and only those with a keen perceptive eye noticed her knee buckling slightly when she landed. Smoke curled from her clothes and burns decorated her arms and legs. Her hair had also not been spared, with half her length having been burnt off from the black fireball.

Her torso and face was left relatively untouched, since she had instinctively used her arms and plenty of Touki to defend her vital areas.

The dark flames dispersed quickly after they had been released, revealing an unscathed and untouched Luke still adopting a casual and relaxed posture, with his hands now behind his back. 

Ghislaine hissed from the pain from the first and second degree burns on her arms and legs, the sleeves of her dignified white uniform had turned into ashes, and so had the lower half of her pants. But the pain did not distract her from her opponent, nor did it dull the rapid and consecutive shocks she had received in that split second.

In the short frame of time she had before being blasted by Luke's Latent Fireball, she had observed through her Demon Eye that Luke was not carrying any magic items. At first she thought that he possibly only had items that did not give off any magical signature before being used.

The spell was also at the level of an Advanced-rank spell! Otherwise, any spell below that level would not have been able to get through her Touki. If it had been stronger, Ghislaine might have been turned to ashes like parts of her clothes rather than just suffering a few burns on her arms and legs. 

Nevertheless, an Advanced-rank spell was not something that could be easily found in any random magic item. Something like a magic item that could let you cast an Advanced-rank spell instantly would be akin to a family heirloom, passed down for generations. Not even the Asuran King's vault would have many of those available. 

It was only through seeing the barrier that blocked her attack combined with the fire spell Luke cast near instantaneously did she understand what kind of a magician she was facing. 

"...You're not using any magic items, are you?" She quietly asked, already knowing the answer to her question.

The faint smile on Luke's face that had not been changed since the start of the battle curled slightly.

"I never said I was." 

His reply stunned the Boreas guests. Though they had spoken softly, the underground hall was quiet enough that they could still hear them clearly. 

"...Did Ghislaine just say he wasn't using any magic items…?" Philip breathed out, not able to believe what he just heard.

"..." Sauros folded his arms tighter, "And Luke confirmed it."

Hilda, while surprised, was not as dumbfounded as her husband and father-in-law. 

"Does that mean he is using magic without chanting?" 

Philip nodded uneasily in confirmation, "Not just chantlessly, even instantaneously. With how fast Ghislaine was moving, not even Saint-rank swordsmen could react perfectly. Yet, Luke not only defended himself with some sort of barrier magic, he even counterattacked right after. He barely needs any time to cast a spell…"

"Barrier magic, fire magic, earth magic and even healing magic…" Sauros added while in deep contemplation. "So this is why master Anthony took him on as a disciple."

"What a terrifying kid." Philip concluded. 

Barrier magic generally could only be invoked through magic circles. Verbal casting of barrier magic did not exist. Anthony had taught Luke Intermediate-ranked Barrier Magic, which was stronger than the Elementary-ranked Barrier Magic that was taught in the Ranoa Magic Academy. Even then, Anthony could only use Barrier Magic through magic circles. 

Through research, Luke managed to reverse-engineer Barrier Magic and created a version that could be cast chantlessly. 

Luke was, in truth, a coward who feared death. More accurately, rather than fearing death, he feared dying pointlessly. 

In a world where God-ranked swordsmen existed, Luke's first priority in developing spells was naturally to create a means to defend himself from extremely strong and fast physical attacks. 

With the help of the A.I. Chip, Luke succeeded. An armor-like defensive spell that could coat his body in a mobile barrier. The strength of it depended on how much mana he pumped into the spell. 

He named the spell: Kemoyin Scales. An homage to the defensive innate spell the Original attained after advancing to become a Rank 1 Kemoyin Warlock. The spell Luke created had, after all, drawn plenty of natural inspiration from the Warlock spell of the same name in its creation.

Blocking the single attack from Ghislaine's Longsword of Light had consumed around 20 points of Luke's Magic Power, and it had been precisely calculated in order to minimize the amount of mana he would need to block it. 

Firstly, although the barrier covered Luke's entire body, most of its mana was concentrated at the point of contact where Ghislaine had targeted. Secondly, the amount of mana Luke used had been assessed to be within a 5% degree of error, similarly in order to minimize the amount of mana consumed. And thirdly, the moment Ghislaine retreated, the barrier was released to conserve his mana.

Even then, was a Sword King's ultimate technique so weak that just 20 points of Magic Power was needed to block it? 

The answer was yes and no. A magician with lesser control than Luke would not be able to do so. Luke had naturally mastered the Kemoyin Scales that he had created, and through years of experience sparring with the Notos Saint-rank bodyguards, he had refined it to a level of perfect control. 

Rather than matching raw force with raw force, Luke shaped the barrier with the precision of an A.I.—redirecting, dispersing, and neutralizing the kinetic impact of the attack with minimal energy.

As a result, a Sword King's strongest and fastest attack had been negated with elegant deflection, reduced to a mere ripple in the air not by force, but by finesse and masterful control. 

Ghislaine exhaled deeply, shifting and lowering her stance, to the point that her left hand was touching the ground while her right arm held out Hiramune. She decided to change tactics. 

For a Sword God practitioner, their school of thought was generally: 'a second strike is not needed. If you can't win with the first strike, then you have already lost'. But in actuality, this was true only to a certain extent. 

If a magician seemingly had an impenetrable barrier that could only protect his front, did that mean that a failed first attack meant the Sword God practitioner didn't even need to try attacking from the magician's rear? Of course not, that would be ridiculous. 

Thus, Ghislaine decided to switch up tactics. Instead of attacking Luke directly from the front again like her usual straightforward style, the Sword King now added an element of unpredictability to her movements.

With a sudden snap of movement, she launched forward in her low stance—not in a straight sprint, but in a spiraling zig-zag pattern, blurring from side to side with sharp, angular turns. Her footfalls kicked up bursts of debris, and every twist of her body resembled a wild animal's savagery. 

Ghislaine spun low, one palm bracing against the ground, then pivoted hard, launching herself sideways like a thrown spear. A heartbeat later, she leapt up high, twisted in mid-air, and came down in a corkscrewing dash, her spare hand striking the ground to redirect her momentum.

To the Boreas guests' untrained eye, it looked like untamed chaos. As though Ghislaine was a wild beast exhibiting an uncontrolled desperate thrashing while caught in the maw of a larger predator. 

But to the trained eye of Grant, Luna and Luke, it was in actuality a controlled unpredictability. Her movements resembled more like a storm of calculated noise. No pattern repeated. No line held. Every pivot, every low crouch, every explosive leap was meant to disrupt Luke's perception, to make him waste mana on misreads, to test the edges of his defense.

Luke's half-lidded eyes tracked her, but his body remained perfectly still. Still the same relaxed and infuriatingly self-assured posture that spoke of unbidden confidence. He made no move to cast, his barrier did not form in response to her testing feints. 

Instead, his mana expanded outwards from the soles of his feet, covering the arena in a layer of his magical energy in lightning quick speed, the purpose of which remained a mystery to Ghislaine despite being able to see the movements of his magical power with her Demon Eye. 

Rather than waste time trying to guess at the infinite possibilities of what Luke was trying to accomplish with magic, Ghislaine decided instead to strike first before whatever effects of the spell he was casting came to fruition!

Her Touki pulsed and flared as she pushed harder against the ground with her foot, and vaulted over his left flank. She then twisted in mid-air, struck downwards with a feint, but at the last second twisted her hips and turned the straightforward stab into a spinning sweep from the other side. 

It was a classic misdirection more worthy of a North God practitioner rather than a Sword King. 

"Ah, how predictable." Luke's muttered words left Ghislaine with widened eyes as the boy's gaze was directed right at her. Her supposedly unpredictable attack was once again stopped before making contact with her opponent's flesh and blood.

Her blade hit something unyielding, a gleam of light revealing small, interconnected hexagons that coated half an inch over Luke's body like the scales of a snake. The translucent Kemoyin Scales had formed not where Ghislaine had feinted at, but where her true attack was really targeting.

From start to end, her movements had been completely seen through by the boy of only ten years…

"Chaos is an illusion. Even storms have a pattern." Luke softly muttered, educating rather than mocking. 

"Air Hammer." Luke did not declare his spells like they were special techniques. His words were softly exhaled, like a thought shared with the wind. 

And the wind obeyed.