Prior to defeat of Vanica, a woman with short dark hair clad in armor made out of the water with devil shape water wings spread behind her as she swiftly moves into the battlefield slicing through the horde of monsters with her rapier.
Sona created streamed of water that cut them into pieces even ignoring the thick chaotic energy. She swung her weapon in high speed resulting into a tsunami of water to washed away the monster. Afterward, those trapped in the water were crushed by the water pressure as it compress until becoming nothing more but puddle.
"They jus keep coming! At this rat I need to use my other balance breaker."(Sona)
"Don't get to frustrated, so-tan your nee-san is here to help!"
Sona sigh seeing her sister wearing magical girl outfit in middle of war as she gather an absurd amount of magical and demonic energy into the sacred wand that Issei gifted. It was a powerful one that would never run of magical energy so long the user is able to keep up.
Serafall then pointed her magical wand at the hundred thousand demonic monsters blasting an absurd amount of glacier freezing everything that instantly shatters crumbling the demonic monster caught in the attack. Moments later an enormous monster gathering powerful blast to attack them but before serafall could act.
"I'll handle this, Maou-sama. Full counter!"
A figure swiftly arrived as the monster fired its attack at the person yet it suddenly sent back to the monster with even stronger forces. It exploded upon impact causing a massive mushroom cloud seen through the battlefield. Thankfully Asia sacred gear able to protect their allies as those who are part of the guidance won't be affected.
"Sona-kaichou I recommend using that balance breaker to reduce their numbers." (Tsubaki)
"I think your right. At this rate I'll exhaust myself and the others as well."
Sona then place his rapier in front of her gradually her outfit change into white, ankle-length kimono with lined patterns. The robe has an attached ornate collar, edges, and shoulder design with long, wide sleeves. There are long, flowing ribbons tied at her back that form numerous large loops.
She has a small ice flower formation at the center of her chest, and a half crown of ice which extends around the back of her head. Sona's hair turn into snow white, and her rapier turns into a katana ice blade. Upon exhaling cause the air to freeze and everyone even her allies feel the intense cold radiating that even Serafall who an expert in ice manipulation felt her sister cold aura.
Sona's eyes opened revealing deep blue eyes with a snowflake for the pupils. The demonic monsters for the first time flinch in fear as Sona slowly raised her blade that made her wide open but none tried to move on place. It was as if everything was frozen even the concept of moving was affected.
"Glacier tempus."
Swoosh! Swoosh! Swoosh!
Everything turn into an absolute zero freezing anything in the vicinity into solid ice returning them into the ice age. It didn't even apply basic science where everything just frozen inside and out as if concept of heat was removed. Sona slowly lower her weapon as horde of monster that was frozen in ices shatter into millions pieces.
"Amazing So-tan! I can't even do that with my own ice manipulation!!"
"Sona are you alright!? Revert or you'll be frozen."
Tsubaki said as her king instantly reverse back into her basic balance breaker. It took a lot out of her using and finishing her attack that could even force Issei to used spatial shift and [Nihility] to escape her power. Sona lasted longer than before as while she was train almost resulted in her becoming ice sculpture that was stopped by Issei interference. Now due to coming a dragon was able to use it multiple times and much longer than before.
Meanwhile, as their battle continues another was happening where a female fallen angel summon countless holy spear piercing through horde of monster becoming purified then turn into dust. She was none other than Raynare who wore black armor wielding an enormous sword.
The creature flew to attack her but they were cleanly slice into pieces by her enormous blade gifted by her brother who had been weaken unable to fight with them. Though, the weapon in her hand serve as way that her brother is helping her through the fight.
She was infuriated due finding out they were the reason why their was great war and how they made her lover suffer throughout the hundred thousand years. Though, A small part she was desperately fighting was because of how she had once killed Issei in the previous timeline and this would act as her redemption.
Raynare wasn't satisfied with Issei loving words and forgiving smile but wanted to prove she heard to happy despites her flaws. She spread her wings then created numerous amount of holy spear then throw them all at her enemies without mercy.
'I am only doing this for myself but for the future as well!"
She was too occupied by her mind that she didn't even noticed a monster appearing behind her ready to devour her. Raynare was about to attack when sphere dome surrounded the creature then flatten by compress barrier. The fallen angel turn to see woman clad in valkyrie armor flying beside her.
"Stay focus Raynare and I know what your thinking so stop cause Issei will get worried again."(Rossweisse)
"I know and thank you for the help."(Raynare)
"Don't mention it now then lets go!"(Rossweisse)
She proceeded to summon infinite amount of magical spells then locking them in each target. Her attack decimated the battlefield with different types of spell ranging from incineration to black hole that devoured them all.
The others where fighting with Gabriel giving support the best she can and being protect by her brave saint, Griselda Quarta and Mirana Shatarova. They slew the monster coming towards their master instantly killing them with ease.
Another person great help was vasco strada killing them with a replica of durandal killing the demonic monster with ease. Michael arrived along with Sizerchs decimating the battlefield but far minimal compare to Issei woman but they are still powerful individual and able to reduce the number of monster.
"We must all win or everything will be destroyed!"(Michael)
"Their numbers are getting smaller while out army had only had few deaths."(Sirzechs)
The Maou then saw long spear piercing through the hordes of monster as Cao Cao appeared along with his groups as they began helping reduced the army. Georg used his newly acquired tier spell to obliterate the demonic monster like nothing.
Then heracles punch the air with each strike one shot the army in front of him. He then slammed his fist into the creating a massive cracks as the shaking the ground and killing the monster with the force of his fist. Leonardo then used his annihilation maker creating monster to counter the demonic creature.
Meanwhile the evil dragons started destroy the landscape with each of their attack pushed the clouds away while the demonic creature fall like flies. Azi Dahaka used his own forbidden magic casting a powerful ray of pure darkness destroying the land.
"Hahaha this is truly an amazing place to fight! Come you lot and show me your might!!"(Azi Dahaka)
"You're too barbaric you old fool."(Apophis)
Apophis who was nearby manipulated the darkness wrapping themselves into the body of the monster then clenched her hand crushing countless monster. She smirk at Azi Dahaka being able to kill more than he can but came to stop When Crom Cruach arrive easily killed few hundred thousand of the army grinning at the result.
The two evil dragon god looked at each as they vanish then began fighting themselves while killing the creature as an aftermath of their quarrel.
Crom cruach saw the two fought and decided to join in as the minion was too boring. If anyone saw them they would immediately ask how can they be so carefree but seeing their power they would likely run away.
Sariel and the other administrator didn't participate in cased the dark apostle escape into the human world while Ophis and Great Red remain to protect Issei parent and Lilith. As for the enslave gods they remain to protect the world.
Then a crack in space occurred allowing everyone to see Issei and Nyarlathotep battle seeing the result of their battle. They felt distraught seeing Issei was about get defeated but everything change as Issei regain the upper hand.