"How did these items get made if there's no way to learn magic? Are the magicians homeschooling their children and not writing any books? How did you learn?"
"Half this stuff is antiques," says the shopkeep. "Look, asking me a dozen times isn't gonna make the answer more to your liking. I don't have Hogwarts in the basement, deal with it."
"But where do you get the stuff that isn't antique - who made the Avalon itself? - isn't anybody panicking about the medallion supply? -"
"Kid, nobody knows how to make medallions."
"But some people apparently know how to make luck charms and protection amulets!"
"I'm not going to give out my suppliers' personal information. I wouldn't do it even if you weren't annoying."
"There have to be books -"
"Does this look like a library to you?"
"A history of the Extinction War, looking for clues about medallions. I wonder if we could bring anyone of either of the particularly relevant species back without reigniting the whole thing."
"Apparently dragons were immune to any magic they wanted to be. Including backlash from miscasting spells."
"Yes, it's how they managed to hold their own against the sphinxes, who were extremely magic."
"So the sphinxes had... magic shortcuts, which they could only use indirectly, and the dragons had. The biggest R&D corner-cutting advantage ever?"
"There was something about self-healing, so it wasn't all indirect, but apparently."
"Apparently they got their hands on the diary of a survivor--a dragon-faction griffin survivor. He didn't know anything interesting about runecasting himself, more's the pity, but he had seen dragons brush off hostile magic like it was nothing."
May reads, murmuring softly: "My commander could in extremis write runes at random and speak to them as he would a soldier, trusting his touch to guide them away from unwanted magic; if his results were less powerful this way at least they took only moments to achieve, when we found ourselves without our preparations or references... Holy shit."
"I know. It's not anywhere near relevant yet, I suppose, since we don't even know if resurrection is possible yet, and even then finding someone who wouldn't just start the whole mess over again--I suppose just never resurrecting any sphinxes might do it, but I feel somewhat leery of choosing sides in this whole thing, even retroactively--but holy shit."
...
"...Is there literally anything about you that isn't calculated to be maximally amazing, holy shit."
"That's--you--" he breaks off. "I am retroactively halfway worried about you. If a thing that everyone thinks is true were true then you wouldn't exist. I know it's irrational but my brain is screaming that you had such a close call--and oh my god this is going to be amazing, you can--" he breaks off again. "My brain is halfway screaming with retroactive terror and half with amazed delight. It is very confusing."
"If any historical event far back enough had happened differently most people wouldn't exist, you know. But - don't tell anyone? The way critters and medallions work there could easily be sphinxes the same way there's - me."
"...I won't. Although we might want to do less initial spellcasting in public. Especially if we're not as careful about checking the spells before we incant them."
"Yeah. ...And this means that if I test a thing the results are not necessarily reliable for you."
"Not necessarily. It might just - work and lack some side effect it would normally have. This also calls into question the 'can we just not intend to cast and therefore not cast' result, I was the one who tested that."