*
"... You guys should leave quickly. Who knows how long more the structure will last." (Arugawa)
In a rare instance, this guy wasn't being unpleasant. They hadn't interacted much, because most people tend to stay from him. He had an off putting personality that even his semi decent face couldn't save. It wasn't hard to see why, he treated real life like a dating sim. He was strange and avoided but just barely outside of being hated.
Yggdrasil couldn't remember the last time he heard him talk, Lastia must have asked him to stay away a long time ago. A rare show of compassion, his face contorted as he lifted his feet towards the exit.
"... See you." (Arugawa)
His short blackish red hair flitted through the door with the last of his presence. Another rather withdrawn individual, Ed or Edward, followed next. He was the only person anyone could call Arugawa's friend, he didn't like to talk to others much but felt just at home with Arugawa. Arugawa didn't speak with him much either, he mainly harassed female students with his delusions, and strangely stopped if the recipient ordered him too. Most people found him delusional but didn't know how to fix his problems, while Edward was oddly able to coexist in his world.
"... Akira, go on ahead. We'll catch up. Please. " (Yggdrasil)
"What are you planning... I... I don't want to see classmates die doing something foolish. Please, just evacuate with me." (Akira)
"... We will, we just need to... Rendezvous somewhere else first. We'll meet you, promise." (Sariel)
In a gentle tone, Sariel mollified her. Akira was one of the girls believed to only have an interest in fashion and design. People look towards her for advice and she seemed to have a genuine passion to go further in this industry. Celia on the other hand, while in a similar vein had a different role. Celia wanted to be a model while Akira a designer. Most would think they complement each other because of how well they get along, but they're determined to forge their own paths rather than stick together.
Some would be cruel and say Celia had no chance. The industry is too competitive, that girl might not have the capability to commit. Despite the disbelief, Akira took her word and began heading off. The moment she left the next corner, they transformed and left through the hole in the ceiling. It all happened so fast, none of the students rushing down the hallway caught on. It had also begun clearing as most students have made their way down during the course of their conversations.
Standing on the roof top- they were greeted with a heavy bombardment. Forming a blade with {Feed}, Yggdrasil sliced apart the shells before they made contact with the ground. Her great sword extended greatly, resembling a whip more than a sword as it tore through the air. Explosions chain across the middle of the sky, filling the stratosphere above the school with white smoke and violent flesh tearing pressure. Her skin was peppered with hot air raining down as she kept her gaze above.
"Magic based, they detonated upon contact. Sending magic out this far is like giving the autonomous command of 'land on the target', it's a little like following its own coding.
Arin, your bullets can repel them." (Yggdrasil)
Conversely, it'd be hard for Sariel to deal with this kind of attack. Indiscriminate and wide ranging explosions, this was a weakness. Discovering it now was good, countermeasures can be prepared.
Arin summoned her gun and began blasting pellets of amplified mana. {Barter} allowed her to create these pair of revolver like arms in the past, the item itself is a magical artifact not unlike Sariel's sword. It operated by channeling Arin's energy and amplifying it into a harmful bullet aimed at killing by piercing a single point. These revolvers were special in that their toughness and ferocity corresponded with her level of magical energy, if she put more energy into it, it would be reinforced appropriately.
In that regard, even if the base damage was lethal enough, if anyone could survive that kind of attack, she could control its lethality. Sure enough, each shot finds their target in time, interrupting the second volley. In terms of threat level, each artillery shell was like the full force attack of a C grade threat. Even the weakest of them, Sariel could easily react and divert these shells. Were they not being taken seriously? Or...
"Below. These artillery shells are set on a timer. They predicted us down to our timing of arrival..." (Sariel)
Setting up magical artillery, bombarding them... Even if the lethality wasn't that serious for them, it would be a significant issue if it had been anyone else. In this era, magical girls tended to reach C grade towards the end of their careers before retiring. The existential threat of Traces didn't constitute enough of a problem for them to grow stronger, correspondingly the Traces also capped at C grade. These shells were powerful enough to exhaust a team of normal magical girls.
Yggdrasil owed it to Lastia's unique constitution, growing stronger everytime she defeated a heavenly king. Arin had some other concealed mysteries, she likely reached A grade before revealing her identity as a magical girl to her. Sariel was the only one who was normal, even then she was on the upper verge of trespassing into B grade territory. The opponent this time seemed to be highly intelligent, drawing them out to the rooftop and bent on exhausting them. Below C grade and they might have simply died to the shelling.
Yggdrasil planted her great sword into the ground, facing the entrance of the rooftop. They hadn't taken the entrance so it wasn't cleared of enemies before hand, looking at it from that perspective it should have been obvious. They were being observed. Intelligence? Are they gathering information about their abilities? They wouldn't be able to figure out based on the information they've shown so far.
There's still a chance.
"Sariel, conserve your energy. If you can, don't use your skill at all." (Yggdrasil)
Physically, she was weaker. Transforming into a magical girl naturally multiplies your basic attributes like strength, toughness, speed and other such things. Even magic, you get to access a far larger pool of magical energy, enough to activate skills and so on. Otherwise, a normal human being could never have enough to power a skill. All of this to say,Yggdrasil firmly believed even with {Feed} and {Barter}, {Swap} might be the strongest.