*
"UUUUWOOOOOOOAAAAAAAAHHHHHHHHHH!!!!!!!!!!!!" (Ledia)
She copied Himei's move, conjuring the continent destroying sphere of energy from last time in front of her, before throwing her fist into it with all of her body and soul. It felt like she was punching through a wall of glass as it shattered and graze her flesh, shattering her wrist and powderising her finger bones. The skin on her fingers had become blue as blood vessels burst and release large volumes of blood. She really was doing something akin to coating her arm in glass shards.
Enduring the pain, she let the monumental dense ball of energy coat her body, combining it with the momentum derived from her shoulder and waist to launch a successful punch. It shot forward as fast as she could pull it off while being accurate, rushing at Himei's face before landing in her palm. The residual energy flies out between the gaps in their fingers, resulting in a nuclear explosion leaking out and dying the sky black with smoke and radiation.
"...?!" (Ledia)
She discovered something new, she could manipulate the radiation with her first skill. In an instant, the nuclear energy shot back at the 2,aiming at their competing fist and palm. Resulting in a secondary explosion. The world became silent due to the high density of energy, in other words their ear drums were blasted to deaf.
With a flick of her finger, all of that destruction vanished. A smile cranked itself up upon Himei's cheeks. She easily removed any debris, radiation, pollution or anything harmful for the earth in an instant.
" Final skill, [Perception dances under the sole observer of the universe]" (Himei)
As if taunting Ledia, she spoke in a calm and composed voice. It chimes through the air like a clear melodious bell, almost mesmerising like a siren's enchantment. If not for the extremely high adrenaline and steroids in her blood, produced by a magical girl's body during battle, she might have gotten distracted.
"...?! Charm magic?" (Ledia)
"Fufu... Well, there's a lot more. So it'd be a mistake to think that's all I could do." (Himei)
Her fingers sliced through the air, amputating Ledia's arms. Ledia had already planned to attack, so despite not being able to react to Himei's ambush, her body pushed forward and exploded into flames.
"... That's good. One of the advantages of using your heat magic... Is that you don't need your limbs to attack." (Himei)
So she says, enduring the heat like an inconsequential summer breeze. There was a clear gap in power between the 2, between S and SS grade, finite and infinite. It was something no amount of training or specifically honing one's own skill would help. There was no longer any point to making Ledia stronger in the conventional sense of refining one's techniques, strategic thinking and combat prowess.
That's why Himei has taken to sparring with her instead, the only thing left that could stimulate exponential growth... Would be experience with death. But this sort of harrowing experience has a prerequisite, it stems from the fear of death so naturally... Kaori's time rewinding revival or Himei's superimposition revival would cause it to become useless.
The sensation and fear of death would still be present, as it was human nature to possess it. However, the removal of the consequences of death through revival, would cause this unconventional and morbid growth stimulation to continuously diminish each time she revives. This form of growth lies primarily in the meagre possibility that when coming close to death... Her soul will be washed in a deluge of desparation, which will prompt her mind to think up a solution.
It must have been the tiny side of Himei that remained similar to Kaori, who suggested this. As in Kaori's case... She had thought up of many nascent techniques in the heat of battle, and managed to put them into use to give her the slightest edge necessary to win the fight. Thus, the one objective in this spar... Is to induce so much desparation and thirst to live that Ledia conjures the ultimate technique to bridge that gap.
Ledia grows back her arms before shrouding them in flames as well. She hasn't used much of ice attacks by utilising her first skill to take away energy, because at this stage, the enemy's endurance stat is so high that sub zero temperature would do nothing. Her magic isn't fire or ice magic wherein if she shoves in more magical particles to increase the quantity of magic energy, it will enhance the attack. Her magic was simply the transfer and conversion of heat energy. Reducing the temperature to sub zero would do pretty much nothing to the strong, it would only be useful to immobilise the weak whereas the average magical girl might even be able to shrug it off.
On the other hand, there is no limit such as sub zero temperatures when it comes to increasing the temperature instead. She can keep increasing the amount of heat and energy, sort of brute forcing by compacting the energy and increasing its density so that it erodes anything away.
Normally, magical particles are a non physical substance, it has no mass and can pass through everything. It even passes through time and space, the world has an infinite stock of magical particles as a result, and the limits of controlling these particles are actually imposed by the wielder's body having the inability to handle anymore magical particles. That's why Ledia's exponential augmentation of her body stops at S grade, her body cannot hold anymore augmentation as it will spill out.
Kaori can overcome this limitation as her first skill's manipulation of gradients can control the movement of magical particles, and contain them within her body like a cage, then try to tough out the erosion of her body by the excess energy. But for Ledia she can't contain them in, they will leak out by voluntarily. Yet, heat energy has a physical effect on reality, it will usually pass through magical particles in daily life. In other words, it can pass through shields made purely of magical particles. This was another advantage, though shields of pure magic are rarely employed.
In other words, enemies have to prepare to intercept the heat energy by converting their magical particles into something physical. The heat can bypass a magical girl's magic defences which would otherwise impede fire magic, which was fire imitated by magic. So the heat attacks a magical girl's physical defence instead, and the opponent's magical particles will have to be funneled into their endurance stat to fend off the physical erosion of their body by energy and to revitalise their regeneration.
***
That's why...
Gravitational potential, hydropotential, light, sound, chemical... There were many other branches she could still reach out to and grasp with her first skill alone. It was impossible for hope to die out with these many possibilities.
'... Ordinarily... She would have lived a mundane life. Sure, she was talented enough to awaken at C grade, but it would take around a year for her to reach B or A, maybe S after a decade. She wasn't meant to fight the destroyers, their destinies did not align. This was the doing of Kaori, using the gradient of their destinies and forcing them to collide with one another. ' (Himei)
An interception of fate, a possibility not meant to exist in this world.
Himei's senses began to distort, her overwhelming observational ability began to have holes perforated into it. Converting energy to sound and light to mess with hearing and vision, a patch of red streaks across the sky like paint along with a myriad of other colours, imitating a chaotic basket of fruits as colour stretch across the sky with little sense or purpose.
"First skill [Heat sets the entropic destiny], prototype technique - chaos simulation." (Ledia)
A strike on the senses that work precisely because of Himei's transcendant ability to observe, these random lights of numerous colours dotting the sky and those sounds of gale, cries and scratching could only be perceived by a single person, Himei. The first step was not to manipulate the intricacy of this hallucination, but to fine tune it so only Himei can observe it. If a normal person were here, the sky would be gentle blue as usual with a mix of some fuzzy clouds. These illusion were invisible to the world, yet infinite to Himei.
As a result, she honed the ability to create a different hallucination for each person... An ability meant to fight a crowd. These were not illusions in the traditional sense either, illusions were in essence a show, an exhibition to the sense with no real substance behind it in actuality. But these stimulation brought on by Ledia's magic had substance, she was simply able to tailor them to the individual, giving everyone a different experience. The lights and sound still manifest in reality, they just do not reach the receptors of non targets, hence aren't perceived by them.
This comes back to subjective Idealism. If only one person perceives a subject but everyone else does not,or are unable to, is the subject real? Is there any meaning to being real if one is unable to ever make contact with it in their lifetime? These stimuli that she conjures are all real, there is nothing anyone can do about it. Anti illusion or mental protection magic can not do anything about it.
A magical girl's senses, their receptors or unquantifiably more sensitive. It's easy to overstimulate them if not for the magic simultaneously augmenting their endurance to stimuli and increasing their computational ability to perceive and comprehend things faster. This might have worked to confuse others, but...
Himei's computational ability is effectively infinite... It was like slinging a snowflake at a snowman, while confusing at first, it wasn't much of a problem to Himei. It was just that, confusing. To the same degree that a person would feel when it rains despite the weather forecast suggesting a sunny day. The issue was that... Himei was one of those individuals who could view the world in third person...
Using gravitational potential energy, Ledia accumulated potential in Himei and executed it, causing Himei to sway through the air like a rag doll. This would usually cause a person to be utterly confused and possibly disoriented, but Himei's observational capability once again overpowered it. There was no psychological attack or trap that could fell her, the only way to defeat Himei was to straightforwardly use destructive power... Which was something the destroyers had in spades.
The destroyers were a mythical folk tale told by countless generations of individuals in The Eye God's lineage. One of Himei's ancestors used the power of the eye, clairvoyance to read the destiny of the world itself. It would end with the arrival of the destroyers, hence this was the name given to them by Himei's ancestor.
Back when fighting Hikari and Kaori fused with Himei, she inherited this bit of memory from her and knew the destroyers existed. That was why... The psychological extradimensional harrassment started from a week before the destroyer's arrival and Kaori knew about the culprit behind them.
"You're wrong if you thought that was all... Prototype technique - chaos bundle." (Ledia)
If she tried to hide within the splotches of colouring lining the sky, it would be futile since Himei can see through all of it. So the optimal form of camouflage that she employed... Was to actualise countless copies of herself while not letting up on the paint over reality as well. Bundle theory, a line of thinking that objects in the universe are simply a bundle of perception values. The object does not truly exist in reality, but the stimuli that it gives does. We take in that stimuli and interpret the object. With convincing enough light, sound and heat manipulation, Ledia can perfectly replicate her own stature.
She has not conjured any physical object for the entire battle, she couldn't. But she could full the senses by conjuring the associated stimuli, fooling the target's brain itself. It took a single layer of thought to comprehend the stimuli's existence, and a secondary layer of inference and deduction to pinpoint the real Ledia. The right amount of light creates the figure, the appropriate wavelength of sound sets the atmosphere, the perfect amount of heat fools the world's sense of touch.
A third layer... A vast infinite computational power observes and dictates the world. Himei can simply choose a single mirage of Ledia and dictate that it was the real one while making all the others the mirage, it was that simple since she can perceive every detail within the universe. But... She can also thwart Ledia's perfect mirages by simply reading every observable value around and inside them.
The mirages were perfect, too perfect. Perhaps the real one would have imperfect values. She was conjuring so much magic, the values were bound to tend towards the paranormal instead.
She could also eliminate all the mirages at once. There was never a limitation, Himei could effectively thwart this technique in so many ways. There was still a long way to go.
She tap her index finger on the forehead of the real Ledia, much to Ledia's confusion. She decided to identify the real one and make a show of power by simply seeing through all the mirages. X-ray vision sounds conventional and mundane for an eye-related magic power, but only one Ledia in this vast sky had flesh and blood...