*
{Sorrows of a beloved maiden}, how long has this skill been active? Maybe since the start. She's been continuously using {Swap} after all.
Punch after punch, she slams her knuckles into Eterna's durable body. The speed of inviolability, it's something she knows all too well. The unprecedented dazzling brilliance of Lastia, the unending warmth of security that Arin emits, the golden confidence of hope brought by Yggdrasil... She's been so used to chasing after something unattainable from a position of the 'ordinary', she can see it from a mile away. With a single step, her left heel digs into ground and splits a hole in the jade sky. Arching her arm back, she throws it with all of her spirit.
Eterna sucks air into her throat and throws her own, fist meets fist, splitting another crack into the jade environment and releasing lightning. One after the other, their punches meet without fatigue, the nearby jade suffer cracks and tiny crystal debris fly into the air. A magical girl brings hope, a magical girl brings change. They can be defeated like anyone else, even so they reserved the right to dream of an idealised future. After all, they are that kind of being.
A maiden chosen by destiny. An ordinary maiden, she claws her way up without pause. No amount of training is enough for her, surpassing the era is just a pit stop. Her friends come from another era, that much is clear to her, as if the information had been uploaded to her mind when she achieved this new power. They have more mysteries than answers that she knows of. She is the only native of abundance. Reincarnation? Is that how they've arrived at the same time period where she was born?
Regardless, the person she wanted to surpass the most... It was Yggdrasil!Lightning sparks fly uncontrollably out of her enclosed fist, her face and body tensed every muscle. Her joints bend and creak with pain, but her soul protests the most. Her life's meaning, there's nothing fancy like saving all of her friends or protecting her loved ones. What she wanted from the very start as a senior magical girl... Was to be stronger than the others!! She lives to surpass. She lives to protect.
That infinite focus surpassing time and space managed to let her inch a slight gap in time, moving faster than Eterna by a miniscule amount.
"Urgh!!" (Eterna)
Her arms cry under duress, Eterna was being pushed back. Incomprehensible! How was this possible?! Yet she couldn't travel back in time and stop all this from happening. There is no past, this is the mirror world. In a reflection, there only exists the present. A mountain of circumstances unabashedly favouring one side, mirroring her crowning as the ruling deity... Only this time the circumstances were stacked against her.
With a kick, her body was sent flying. Before she could land, a fist slams into the back of her head. For a moment her vision darkens, and her view felt disorienting. Had she been knocked out before? She didn't know, but she was alarmed. When was the last time she felt danger? Sariel was the second entity she didn't have a conceptual advantage against.
"Repent with your life. Apex of the universe, you are the just the first step I need to surpass." (Sariel)
Her trusty sword made of Trace parts materialises. Enchanting it with her newly developed magic, she thrusts it into Eterna's back. With a single swing to retrieve her sword, Eterna was split in half vertically. Blasting her sword into the ground and enshrining it, it releases a pillar of light that grows and consumes at a rapid pace. Using the jade filled with human culture, it recognised the crowning deity as a traitor, subverting a portion of her authority to eliminate her body and soul.
Human culture unites under one banner, the representative of humanity. A title with no power unless it were to fend off an external foe, or be misused by force. The representative gets to dictate who is a threat to humanity and bear its power at them. Not only was Sariel a human, but she fought until her own power was recognised. It determined that she would be a stronger representative if neither utilised its power, so it no longer crested its blessings on Eterna.
11509 years of human history fall apart, the emerald green skies rot and wither into insignificant specks, blown into the winds as dust never to be seen again. The world darkens, deeper than the night, a starless expanse wraps the entire planet. If what they experienced before was the infancy of a galaxy, this is the power befitting an entire universe. It wasn't strength Eterna could use right away at the beginning of battle... Because it isn't her power.
They fought Eterna, owner of the garden and crowned deity of tranquility. As the reigning god of this world, she subsumes every other divine authority, a chief deity of a one person pantheon with every access under the cosmos. Now they fight Eterna, sole survivor of eras past and dead stars. The definitive end of origin and mystery, cosmos violator. They were two sides of the same coin, a face that only surfaces when the other collapses under its own weight. Twin authorities of the exact same stature and power but of opposing natures. One builds up culture and one destroys.
A black dress adorns her body, it's edges curved into countless petals. A black veil covers her full face, her expression hidden in her masks. Cosmos violator, a being that 'sheds' its identities with an unknown origin. It's harsh, but she radiates an 'inhumane' aura, it's difficult to ascertain if she was ever human in the first place. A foreign being that one day slipped into role of a rule, the idea itself fills one with despair, to be controlled by another and not even a human at that.
However at the end of the day, these were just ideas. Her silhouette begins to dissolve abruptly, clothes, flesh and hair. All of it melts into a viscous black liquid that drips towards the ground, the sea of fractured jades lining the battlefield also began to follow suit, forming a whirlpool at the centre.
"... She's escaping to reality. I don't think it's possible, but I won't be able to bring your memories to the real world. " (Alice)
"... That's fine. I can {Swap} myself out. My comprehension has gone up a level." (Sariel)
... If only we killed the Eterna here, whom was weakened in this mirror world. Then {Swapped} her out with the one in the real world... This might be the end, but even so... Sariel wouldn't give up.