*
Finding a gap in the assault, Ledaine speeds off, followed by Yggdrasil. A white comet followed by a black comet race across a backdrop of white, desperately vying to dye the world in their own colours. The sky was already white, Ledaine hadn't won, but he was winning. Humanity was suffocating other his magic, which drew out all the suffering in their lives. They would scream and thrash, with no room to inhale or exhale. After the first couple minutes, all of them had gone unconscious, leaving the world to be only inhabited by magical girls.
Yggdrasil chases Ledaine, but no matter how much she sped up she didn't seem able to catch up. This was the difference between an A grade a S grade, she might have been fighting a losing battle from the start. She might be burning through all of her magic right now, but to Ledaine this wa less than 10% of his entire mana pool. Switch to long range armament, compressing bullets.... Fire!!!
Simultaneously, hundreds of dark red bullets form and shot towards Ledaine. Barely maintaining the same gap, she unleashes saturation fire while adjusting her trajectory. If she got hit by her own bullets it would be most foolish. The bullets rush forward as fast as she could send them, though at this velocity it wasn't really possible to shoot them.
At present, they were moving far past the speed of sound, missiles and aircraft. No amount of 'combustion' could boost the speed of her projectiles, the only way left is to manually inject more magical energy and drag it through reality with her mind. It's like pushing a ball rather than firing a gun. The bullets home after Ledaine, some finding their mark but leaving not even a scratch. Just a bit more... Yggdrasil follows closely, not letting up for even a moment.
"{Swap}." (Sariel)
"!? You've already dealt with {Nerve}?" (Yggdrasil)
Twisting forward at tight turns, she barely shouts over the roaring winds. Usually, none of that will get through to the other party. However with both a voice that could overcome the speed of sound, and a sense of hearing that could capture and decipher such esoteric noise flowing at extreme speeds, it barely comes across.
"Yes! Do you... Trust me?" (Sariel)
"Did you need... To ask?" (Yggdrasil)
"GOOO!!!!! {Swap}!!" (Sariel)
Yggdrasil will overcome fate. Fact is, two of them are still alive. Sariel isn't the last one left, humanity might be on the verge of extinction, but things are not past the point of no return. One minute left. Normally, Yggdrasil would have died by now. Leaving Sariel to bring the rest of the magical girls on earth together for one last battle, by that time the rest of humanity would have died. Arin could have found some other method to thwart Ledaine, but she chose to believe in Yggdrasil and gave her another chance. Multiple fates overlap, giving way to Yggdrasil's last ditch effort.
Giving Sariel permission, {Swap} was used on her. Her body shifts forward at a far off distance, allowing Ledaine to fly into her instead. She thrusts her great sword forward, detonating it into a large explosion. The world is no longer suppressing Ledaine, who is an entire grade above Yggdrasil. Yggdrasil was hard to kill, but it wasn't impossible. Ledaine simply preferred to play it safely and wanted to stall until most of humanity suffocated to death.
With another {Swap}, she shifts closer to Ledaine. The angle changes, as if this was Sariel's way of saying to attack from here. She swings her fist, Ledaine swings back. However, before both punches could land, her position changed once more. Her position shifts continuously, each time she lands a hit or two. Gradually, Ledaine accumulates injuries as the attacks grow fierce. She slams her foot, throwing Ledaine into the air, before catching up thanks to {Swap}. Whenever she needed to reposition, {Swap} triggers, as if her mind was being read.
In this manner, they synchronised.
"There's no more time left, {Feed} full power!!" (Yggdrasil)
The world tree surfaces into reality in the far off distance, giving off a faint black luminescence. No longer confined to A grade and the limits of her own body, the tree starts to send the world's magic into her body. To reach the underworld and assault Ledaine's remaining forces, she had discarded Lastia's body and put herself on a timer. Then... Right now she's been alive for more than a minute, all this time it was because she's persisting in Arin's body. The body will start to break down as she shifts into S grade, but with less than a minute left it might not be hopeless to return alive.
"...!? The tree... It wasn't dead. You're..." (Ledaine)
"Shush!" (Yggdrasil)
She swings her left fist, throwing Ledaine further up, before teleporting with Sariel's help. Her assault won't stop. Ledaine closes in with a scythe swing, she blocks with the great sword held in her left hand and swings her right. {Feed} energy erupts with transcendant heat, boiling the heavens under the white universal expanse. Perhaps witnessing the world tree's power, he no longer held himself back.
Ledaine tears through the searing smog with his scythe and leaps through. His blade tears into Yggdrasil's waist as she swings her great sword forward. At the last moment, Ledaine slips away and the great sword's tip barely bites into his arm. Without another moment's hesitation, they swing from their new positions and their weapons collide. Cracks bore into the nascent white world birthed by Ledaine's power, but it repairs itself just as fast.
Swing after swing, destruction and recreation, their exchanges unleashes enough energy to carve ravines and sweep cities off the map. However... Yggdrasil is absorbing all of the resultant shock waves and converting it to more power for herself. No matter how much power Ledaine has kept outside the world, Yggdrasil will counter. Thanks to the tree's presence, the rate of absorption has only increased.
"Divine technique derived from heavenly memories - World tree's embrace!" (Yggdrasil)
Engaging the sensation of when she ascended into a higher being, the tree began to work at limit breaking efficiency. Embracing the universe itself, any and all attacks by Ledaine would be absorbed into more power!