Almys returns, tentatively poking his hand into the Rope Trick to wave for lack of any other way to knock, and then climbing up when there's nothing resembling an objection he can detect.

He's got an assortment of used books, purchased at four different used bookstores in case anybody's looking for patterns.  (It's a noticeable chunk out of his remaining savings, but the used books are saleable-back, and Almys on reflection felt nervous about leaving the trace of a rental.)  Almys lays them out on the dark pseudo-floor of the Rope Trick:

There's a book on Plasma crafting that covers the sub-affinities (Air Fire Light), and a book on Murk crafting that also covers the sub-affinities (Earth Water Dark), purchased at two different book stores.  This is very clever of him and somebody ought to give him a cookie.

There's a smaller book about crafting crossbows.  Hopefully it covers crafting crossbow bolts and hopefully that part you can do without smithing.  From the same store, a really sadly simple introduction to crafting in general, which Almys himself plans to read so he can fake being the crafter slightly better.

A hefty worn tome on magical theory for Tier-3 research magicians or know-it-alls trying to show off, that covers the known laws affecting every kind of affinity magic and even talks a bit about Creation and Uncreation magic.  He actually did rent just this one, this one was too expensive to buy, but at least there's not a lot of interesting lending records pointing at the same person.

Almys didn't quite dare get children's exercises for developing every kind of affinity, that seems to him like too much of a "hey I just found a new Summoned Hero" tipoff, but he can hopefully remember the exercises himself for Fire and Earth, and he's got children's exercises that cover Air, Water, and Light, and hopefully if you know all those Dark isn't too hard or he can get the exercise book some other time.

Carissa is smeared with blood from her efforts to figure out Earth and is sitting intent while she hangs Fly and Haste yet again. She stops that, casts Detect Thoughts. "No problems?"

"No problems that I was allowed to know about."

Thoughts:  He's deduced that those gestures mean she's reading his mind, and while he didn't betray her on this particular trip (nor intend to for later), his mind probably is going to start doing the obvious thing with going helplessly towards more embarrassing thoughts.  Like how he tried for a wide wicked grin and stared at himself in a mirror looking like that, in hopes that he'd feel more like his female self (it worked a little).  Also he thought a few times about how or whether to seduce her but did not see how seduction could possibly be compatible with having your mind read out for seduction plans.

"If I want you I'll tell you." Mage Hand grabs the books and floats them over to her. "I think I won't easily be able to disguise my spells as local spells, unfortunately. I wasn't expecting it to be easy but it seemed worth trying to figure out. And I couldn't work out any of your combat magic, at least nothing useful for opponents who aren't crippled toddlers, but maybe that's because I haven't seen anything but Earth? It feels like I don't have enough pieces to work with."

"Yeah, you're not going to injure anyone by throwing a big clod of dirt at them, right?  I can demonstrate how it works with throwing a Metal bolt, but I'm not sure how much your Spatial walls can take in terms of magically charged impact."

"Wait, what do you mean useful for not crippled toddlers.  Do you mean that you already have a spell that can get crippled toddlers?  How?"

"Yeah, if a horde of crippled toddlers come after me I'm all set." She demonstrates. She isn't interested in keeping her current local-magic capabilities secret from him; it'll mean she improves slower, and it's going to be changing fast enough that the information is quickly out of date, and they don't at this time constitute more than a trivial share of her capabilities.

"Right.  I'd ask stupid questions like how you're able to channel and aspect Earth-affinity mana without anybody having conducted you through the awakening process, or why you already know any Earth spells at all let alone one that does something that obscure, but the answer is obviously going to be 'Summoned Hero' so nevermind."

"You showed me how to do Earth, earlier, with the dagger. I don't think I could've gotten it from a cold start."

"Right, well, if you're talking to anyone who's not supposed to know you're the Summoned Hero, bear in mind that normal people, as children, have a grownup with strong Earth affinity - or whichever basic element - come in and run a lot of aspected mana through them, until they start to be able to feel it, and eventually they manage to do something that feels the same way to them and start to channel.  And even all that would probably be a lot harder if we were back at the start of the world and it hadn't been done a billion times before."

"How'd you know the spell?"

Shrug. "Maybe Tea Guy thought I'd run into some crippled toddlers and need to know how to defend myself."

If he's not supposed to ask, okay, he's not supposed to ask.

...it's a very simple spell, or at least, it looks that way from the effect; he's not enough of a magician that he can sense the detailed structure of her magic.  So there could be a standard spellform for that simple effect, maybe as a piece of something larger, and the Summoned Hero could've run across it by accident while throwing magic around, and watched it snap into the shape-worn-into-reality, and then instantly acquired that Skill because Summoned Hero.

If she's just going around inventing entirely new spells with no worn-patterns for them to snap into... actually he's not going to deal with trying to explain it.  It'll be in the books.

She's not actually sure if that's what she's doing! She also still has no idea which things are worth trying to keep secret even from him! But she suspects after she reads these books she'll be a little more oriented.

She Prestidigitates herself less bloody and takes the books with the care of someone who indeed hasn't found books to be cheap, though the reason in her case is mostly that getting things to the Worldwound isn't cheap.

Does his liege want him hanging out in the Rope Trick or guarding the bedroom downstairs?  He'll probably fall asleep in an hour or two if left to himself.

"I was thinking I'd next send you out for food, actually, if it's not served downstairs, and then you can sleep. I should...probably also sleep soon." She doesn't want to, though; she wants to learn ALL THE MAGIC. The only reason she ever particularly prioritized sleep was to get her spells back.

"...sorry about that.  I sometimes forget food is a thing if I'm otherwise excited.  I'll go get some for both of us."

He departs.

She's never had a minion before and is not sure she understands how it works but she's pretty sure she is supposed to just torture him if he makes mistakes so they can avoid the horrendous awkwardness of him telling her things about his personality and mood and apologizing to her for things.

Is there a Skill for getting the hang of having minions? Probably. People have done it before.

-- anyway. 

Do these books perchance contain the secrets of PHENOMENAL COSMIC POWER.

If she's skimming around in the beginnings, she'll very rapidly learn that all 'standard' crafting, like crafting anywhere before the upper ranks of Tier 3, is all about...

...getting spellforms right enough that they snap into the ruts worn into reality!  This explains the weirdness of the Earth-enchanted sharp knife!  It wasn't really crafting that spellform for sharpness!  It was getting it roughly recognizable enough that it'd snap into the same shape as a spellform cast a billion times before in this reality!

Or to put it another way, the fundamental basis of enchantment in Kekaro is a child scrawling a shape in the dirt sufficiently recognizable that their mother can pat them on the head and say, "Yes, dear, that's a very nice dragon" and correctly guess that it's meant to be a dragon rather than a roc.

So you mostly can't invent new spells, because that'd be telling magic to do something it hasn't done before, and to do that you'd actually have to get it right, and these people don't have Detect Magic, don't have scaffolds, don't have spellform manipulation at all, they can't even tell if they're getting it exactly right, let alone do it exactly right on purpose. 

If you hang a spell slightly wrong in Golarion, it doesn't work, because Golarion isn't your mother.

Is there any implication here that all the supposed extraordinary powers of Summoned Heroes just come from...understanding how magic works? Like, are most new spells invented by them, are the spells they cast noted to be unusually precise and the artifacts impossible to replicate?

None of the pages she's skimmed yet mention Summoned Heroes at all!  If she looks for the parts of the crafting books that are about research and invention:

Upper Tier-3 research crafters will build complicated laboratories and acquire a zillion different affinity mats that they can carve with microscopically exacting precision to do enchantments and spellforms for the first time, and a second time, and a hundredth time.  Then they build a version that can be carried into a dungeon and used in combat, or compete in a competition with a huge prize on the line.  In time crafters who aren't upper-Tier-3 researchers will be able to build smaller less expensive (but still pretty costly and elaborate) versions.

If an item is popular enough despite being expensive, or enough time passes with enough cumulative sales volume, it'll eventually become much simpler and cheaper to make an item that's good-enough-to-work.

The people of Kekaro are not actually stupid!  But they don't have the entire concept of spellsilver and can't just impress a hundred tiny fine exact mana-behavior-affecting properties into bits of an item.  They have to do everything via affinity mats with exactly the right shapes, mated together into larger wholes.  They can do subtractive manufacturing on affinity mats in-place by their wills, introduce carefully curved borders between affinity-mana that's there or not-there, compress it, texture it, within a single mat.  But in local crafting, you can't just take a magic item you're working on, and a smidge of spellsilver, and add in a little pull right there.

There's ways to make affinity mats that aren't from dungeons, but except in some special known easier cases they involve going to lengths like "leave some adamantine in a volcano crater, bathed in Fire mana, for a month".  It's not something you can poke into a magic item in progress.  Well, unless you're a Creation mage, but then most of the rules don't apply to you anyways.  (The particular crafting book she's skimming says this, but doesn't go into detail on how Creation magic works.)

And spellsilver - isn't obvious, actually, if your world doesn't have it. It's very hard to make and -

- some Summoned Hero should have told them -