A young woman, maybe fifteen or sixteen, dressed in somewhat low-tech-looking clothes and sporting more than a few bruises walks into a bar. It's empty right now, except for her. After staring at the exploding stars for a while, then briefly quizzing the bar, she has a nice, tall fruit smoothie for her free drink and solicits a book suggestion. She probably shouldn't stay here too long, but she can't pass up the opportunity to take a break from the rather intense schedule of Witch Wings training.
Someone opens the door. "Uh, hi? What's going on? Something interesting, for sure, but what is it?"
"A break from drills and a free drink! At least, that's what it is for me. This is Milliways, the interdimensional bar."
"Ooh, do I get the free drink? Also, drills?" She inquires. "Oh, and my name is Amy."
"Everyone gets a free drink from Bar, who is a person and also a bar. I'm Gren. Drills are training. My kind of witch loses power fast when we get older, so if you're going to help save the world you join up early."
"Oookay then. Nice to meet you, Gren. Training for what? What are you saving the world from? Can I help?"
"Nice to meet you too. I'm training for the Witch Wings, magical military. Neuroi, are flying monsters that appeared from nowhere and started blowing everything up. I'd love some help but what I dunno what you can even do."
Oh. "That's really sad. I can do magical items, stored spells and potions, but I'm not entirely sure what would be most effective here. I could get my friends to help too, probably. What's the most effective strategy against them that you already use now?"
"Bombs, followed up with starbursts? A magical attack. They're not that tough, but they regenerate quickly."
"Okay, attack spells that work really fast, possibly potions. What's your weakness? I imagine they're slower than you, right? How do they attack? Are you good on defence?"
"I think our biggest weakness is lack of endurance. Our kind of Witch can run out of magic, fights use a lot of magic. Neuroi vary a lot, fast, slow, big, small, maneuverable or not, tough or weak. Their attacks are either physical blades, not that common, or glowing red beams of light and heat. We're okay on defense except for the endurance thing." She demonstrates with a little shield, two rings of blue with vaguely rune-like symbols attached, spinning in opposite directions.
"Mmm, okay, I could call in Flora, she might be able to figure out how to fix it."
She trots to the door, opens it, and shouts, "HEY FLORA, COME LOOK, IT'S IMPORTANT AND NOT A PRANK, I PROMISE!!!"
Flora peeks in. "What's going on?" she asks, confused.
"Whole world's looking out on how to fix it. I'm gonna be buying science books, pricey as they are, bar knows about technology that's waaaay better than ours. Hi Flora, this is an interdimensional bar and I'm very glad Amy agrees that my world could use a little help!"
"They're at war with monsters that fly and shoot beams of light and heat and destroy everything. Gren here is magic, but a kind of magic that quickly fades with age and runs on some sort of magic resource. Can you do your analysis thing and maybe fix stuff?"
"Alright, I can do that, just let me summon my notes, I think I left them out." She pokes her head out of the door, and casts, "Accio analysis notes." Pieces of parchment come floating to her hand. She reads them for a while.
Amy decides to make some magical items for now, including stored runic cutting hexes, and some destructive potions that are relatively easy.
"We each get a few generic things we can do, then a special ability, not like your kind, smells like you can do anything with enough practice. Oh, my special is copying."
"Not anything. There are a few hard limits." She is sad at that part, but cheers up a bit. "So what I'm making now is magical items that can be charged up and will slice the thing you aim at when activated. To activate, say the thing written on them, precisely and loudly for best results. I'll teach you to say them a bit later. Then there's the potions, spill them on stuff you want destroyed. If you think of specific effects you might find useful, tell us."
Read read read.
"Communication stuff. Teleporting. Healing. Magic coffee?" She turns back to her own borrowed books. She is reading, apparently, about revolutionary technological advances such as vaccines and washing your hands, lightbulbs, and refrigerators.
"I could do a pair of mirrors that can communicate between each other! Portal rings, those too, but they're harder, we might need to work together, even call in other people. Healing, yes, healing potions are nice and easy! Alright! There is in fact a thing that could be called magic coffee, but I'd need to look that one up. I can also get you tech with some finagling, just produced for free. Oh, and large amounts of our magic break tech. So we should probably get them separately."
Flora has finished reading.
"Just a thing to remember: don't overuse the magic coffee, it has side effects just like the normal kind. Actually, take notes of everything, starting with that. Let's make a to-do list, task allocation, things and people we need to get, all of that. Oh, and I'm ready to do the analysis. Are you ready?"
"Sure, notes. Bar, paper and pencil? And another smoothie?" She tosses down some coins. Bar provides. Gren starts writing down things. "What exactly is your analysis going to be looking at anyway? I might be able to help."
"Where the magic is, how it works, a bit of everything. It might find out new things, it might not. Works better if you describe everything you already know beforehand."
Work work, lots of healing potions, they're nice and easy.