*
Her legs phase into the air in front of her, movement could no longer be discerned from observation. Unlike normal biological beings, there is no wind up or preliminary muscle contraction in her movements. As an ethereal being on the verge of disappearance, Yggdrasil simply appears where she wants to appear. Destroys what she wants to enjoy.
A translucent white light forms an umbrella shade in front of Ledaine's hands, flickering in and out of life. Her actions look exceedingly light, but they bore an unbearable pressure on the magical shield he put up. It shatters all at once, splattering shards in every direction. A wave of heat brushes past his body, melting his innards and disintegrating his skin to ash.
His body reverts to his most normal state. His flesh is fine, the air is burning up his respiratory system, but he no longer bore injuries. {Cocytus} reversed all damage, boosted by Eterna's authority. At most it could guide the actions of others, coerce strangers into doing his bidding on a level stronger than mind control. Convince the victim that they wanted to do his bidding.
With Eterna's authority, it was dominion over the world itself. It was now coercing reality to rearrange the atoms in his body, having the sheer mental strength to exact atom accurate precision. His computational power was supplemented by the authority, the authority also allows manipulation of those atoms in the first place. In other words, this is not his own strength, but neither did Yggdrasil used hers.
They were both cheaters, and this was simply the outcome. She selects the coordinates, she appears behind him. The air erupts with her magic energy, so intensely did it begin to start burning spacetime with Eterna's authority. Authority over the world is what allowed 'Event's to occur, reversing all Trace attacks and casualties. She was simply utilising that very concept in battle, only to have it disabled moments later. Stopping time for her calculations, digging her blades into space with her magical energy. {Feed} seeps out and spreads across the underworld bunker.
"...!!?!" (Ledaine)
He spins around, unable to be caught by surprise. However, he still groans under the pressure. Space splits around him, throwing numerous small cuts across his body. Miss, they're suppose to completely miss, but they still reach their target even if a little off the mark. Due to Yggdrasil's control over the authority, fate couldn't be completely controlled by Ledaine.
Her right fist closed, the first preliminary movement. At once, they land across every nook and cranny of this bunker. Truly, she did ignore the laws of space and a single punch managed to land on every volume or area available. The entire bunker bursts into reddish black flames, {Feed} ignites for the first time and consumes its fuel(victim) relentlessly. Material, equipment, remaining Traces, nothing could escape except for Ledaine who put up a barrier at the last moment.
He could not protect the bunker, cracks spiderweb across its surface and run deep into its crevices. Laboratories, offices, training grounds, it had all sorts of facilities only to perish into nothing. So much effort into building a homely hiding space, all for it to fall into cracks of spacetime and be lost forever. It's okay, he just needs to bring the battle to an attrition. Yggdrasil has a timer on her life, not him. How long is that timer? It felt like forever since they first confronted, in reality it must have only been a few seconds...
"Have you noticed...?" (Yggdrasil)
Her figure flashes into existence, no... It can't even be described as a flash. She was already there to begin with, within breathing distance. He could faintly pick up a subtle flowery fragrance masked by burning flesh. Whose burning flesh? His own. When did she get there? With time's trickery, it no longer mattered how that question was answered.
"You... You bastard, you're just delaying the inevitable...! " (Ledaine)
He's being dragged along. Along the flow of time. By constantly accelerating, Yggdrasil is operating on a smaller time scale. If her lifespan is a single second, she is observing reality at half speed, it would feel like two seconds to them. Now constantly halve the speed of reality, it would tend towards infinity. Since Ledaine's regeneration has to keep up with the injuries, he was subconsciously adapting to a progressively slower time flow. Time will only continue to slow. He had been dragged into a turmoil of eternity.
"Finally. 11%, I can resume to repair of my core existence. Reestablishing ties to reality. 'Time was on my side' , was it? " (Yggdrasil)
She mocks without a touch of consideration. Undermining the opponent's efforts to zero, bringing his precious bunker to destruction, it all sated her animosity greatly.
" It can't be... You escaped the dissolution of your existence. You, I understand you now.
You are a virus, using Eterna to replicate yourself. The old you has already died." (Ledaine)
And he was a hacker, an external force wrestling for the same control. In terms of danger, Yggdrasil was more dangerous than Eterna, because it meant he could also be infected. So this was a magical girl, he commented in his heart. In the same moment she gained a single percentage of authority, she recreated herself. The old her however has died, having dedicated all power into the replication. His efforts have similarly not halted.
"12%, let's keep climbing until we reach oblivion. There is a limit to your running after all." (Ledaine Termina)
She won't stop rebelling. It's what she was best at. The battle resumes, time slows to a fraction of a crawl. She slams her foot into his chest, an energy explosion scarves out his flesh and blow his heart out. His body disintegrate fully, but also reassembles in an instant. He is a living Trace, not a deity. The only reason his perception of time and magic can keep accelerating was due to the classic combination of {Cocytus} and Eterna's authority.
It pulls and twists fate, it had begun pulling him from the start. It couldn't stop, or he would die. He was truly dragged in by the enemy, an overwhelming force that overturn the flow of destiny. It was the only solution to his intricate manipulation of fate. Effective too. His body can no longer react, his mind simply perceives and he regenerate or puts up a shield. His body is frozen, lest he disintegrates it by moving at a velocity it cannot endure.
His sanity creaks under the spiritual stress, but his resolve does not falter. Let's see who runs out of gas first.