Step one for any project: Gather requirements and determine scope.

The primary goal is to detect magic. I need to be able to detect low-intensity magic, as would be used for an alarm ward or to animate a minor undead that’d destroy evidence by, for example, setting a fire inside a safe. I need long-range detection so I don’t set those traps off with my presence. I need a solution that works through walls. I need to be able to do it on the go, this can’t be a laboratory solution.

Non-goals include magical stealth, precision, modularity, and speed. I doubt this necromancer is doing anything more fancy than ordering an undead to listen for intruders. At this point I only need to know where a trap is, not what it is or its precise details. I can deal with those in a second iteration or with further spell research. I’m currently going for a “babby’s first spell”, I do not have the domain knowledge to start building reusable components. And it’s probably fine if casting this spell takes a half-hour.

The biggest open question is about specificity, the ability to distinguish different magics. I might need that to pick a trap out of, say, a storage room with preservation enchantments on it. However, since I don’t yet have a way to detect magic in the first place, I have no idea how common those effects are, how confusing they’ll be, or how difficult that capability would be.

Scope: I have four hours to get this working. Otherwise, insufficient domain knowledge strikes again; I simply don’t know enough to predict how long this’ll take or where else I could spend extra effort.

Step two: Consider options.

I could develop a spell myself. I have an extremely rough idea of what a detect magic spell would look for. If the grimoire is correct, all I need to find is concentrations of mana that are dense enough to affect the world. If I’m correct there’s more complexity than that, but I doubt the grimoire is that wrong. The problem is that I’d have to do a colossal amount of basic research into the behavior of mana to develop a theory of mana dynamics that explains spellcasting, develop a method for engineering mana patterns with specific desirable effects, and then apply that method to build my goal spell. The upside would be that I’d understand exactly what my spell does and how it works.

I could try to do it by the seat of my pants. I even already have a proof of concept - whatever it is I can feel when I tried to cast the example spell and how that sensation changes when I’m successful. This is something I’m probably going to have to learn to do eventually. However, it doesn’t seem that the capability has much range, I don’t know its sensitivity or specificity, and I don’t have a structured proposal for improving its performance.

The other option is to look through the book to see if it has a chapter on detecting magic, see if there’s a ready-to-go spell in the back, and assume that its guidance is close enough for my purposes.

I take a break to survey the scenery again, hoping a brief break will jog loose anything I’m forgetting. There’s not a lot to see, sadly, thanks to the dense hedgerows that parallel the road. I keep an eye out, though, and soon enough a break in the hedge lets me see a small house in the middle of a tilled field. A man in dirty clothing stands in the middle of the field, weeding or planting or doing one of the hundreds of pre-industrial agricultural tasks that made it such a grueling profession. I go back to my thinking.

Step three: Select a proposal.

I have four hours, almost no equipment, and I’m doing it while walking.

DIY isn’t happening.

Improving my fingertip mana sensors would take too long and is unlikely to work.

That means I’m reading the book.

I mean, I’ve known all along that that was going to be the answer. My gut told me within half a second that I was going to be learning a spell out of the book. But I’ve learned that no matter how strong my instincts are it always pays to do the analysis. I almost always find an option I hadn’t considered until I started brainstorming, uncover a problem because I’m comparing multiple solution line-by-line, or just come up with a related idea that’s not immediately relevant but improves a different project down the line.

Anyway.

I flip to the book’s table of contents and look for anything relevant. “Philosophy of Power,” probably not. “Ethics” is almost certainly irrelevant, and even if wizards had anything like a sense of responsibility I suspect the engineering ethics courses I took in university would have done a better job. “The Flows of Mana”, near the back of the book, is promising; hopefully it’s a more sophisticated treatment of mana dynamics than I got in the overview chapters at the beginning. I also decide to skim a few chapters with titles like “Leylines”, “Natural Mana Users”, and “Accumulations of Mana”.

Those only take me fifteen minutes or so. It seems that, despite what the recess monitors told me, my habit of walking in circles while reading books after lunch really has prepared me for real life!

Of course, my task is made much easier by the road, which continues to be flat and dead straight. I’m also not having to pay attention to any conversation while reading, which helps. Admittedly, I hope that that’s because I’m conspicuously ignoring them for the moment; my experience is that teams that don’t talk much are kind of unpleasant. We travel a ways down the road, the town diminishing in the distance behind us. The scenery doesn’t change.

I keep reading.

Unfortunately, the book’s shaky grasp on theory strikes again. The only really useful claim is that mana gets more complicated as its concentration increases. In particular, it says that many of the “elemental aspects” are only possible at higher concentrations. What’s really interesting is that the book organizes aspects not in a smooth gradient or by giving hard numbers for each aspect, but by grouping a selection of aspects into “tiers” of power. This immediately makes me much more confident in the existence of these aspects, though I still seriously doubt that the book understands what they actually are or how they work. It definitely sounds like some kind of dynamic system with multiple metastable regimes that mana transitions between based on the local density.

Normally, at this point, I’d be looking at something while I pondered, but right now there’s nothing to look at. A few people pass us on the road, carrying logs or crates or the like, but that’s not new. The hedges go past, I catch glimpses of the fields behind the hedges, the sun shines down on us from the wide blue sky, we keep trudging along.

The real question is what’s causing those discrete transitions, if they exist and it’s not just insufficiently precise measurements by the grimoire’s author. I still haven’t seen any objective measurements, after all. Maybe mana is a cellular automaton and some rules just don’t happen until you have enough “live”-ish cells in one place? Is there a periodic table of mana atoms built out of mana particles and all mana-elements past the first period are radioactive and can only be obtained by concentrating mana until it undergoes fusion? Are some of those elements actually the same kind of mana in different “phases”, the way steam and ice are the same chemical at different temperatures? Maybe it just straight-up changes modes and mana above a certain concentration has totally different “laws of physics”.

I don’t have enough information yet. I really need to get a lab together so I can start digging into this objectively and without working through a grimoire of questionable quality.

Maybe a tower. I’d like a tower. Towers are classic for a reason.

That’s not to say that the rest of what I read is totally useless! For example, I learn that mana isn’t subject to gravity. That’d be more useful if I knew how gravity behaved here - for all I know, there’s a God of Gravity literally holding me to the ground by grabbing my soul with a tentacle - but it still probably simplifies things somewhat. Empirical approximations should work for my purposes, since I’m more interested in engineering than I am in low-level physical understanding. I also learn that you can’t directly interact with another mage’s spells because each mage operates in their own “realm of mana”, which makes me feel like this Gift was designed rather than discovered but isn’t directly useful for engineering.

The chapter titled “The Flows of Mana” turns out to be a geography primer, of all things. Ley lines and the like.

On the plus side, now I know what the planet I’ve landed on looks like! Let’s see if I can find the Republic of Eld.

…Nope.

I also can’t find anything that might be called the Kingdoms, which is the only other polity I’ve heard the name of.

“Hey, Heather, how old is this book?”

“I don’t know. Why?”

“I can’t find the Republic of Eld on this map.” I turn so I can show her the page I’m looking at.

She peers at the map. “That’s not a map of Land,” she says. “You can tell because the lines are all stretched out at the edges. Must be the Visitor’s original world.”

“Oh,” I say. So I still don’t know what the planet I’ve landed on looks like! Darn.

Hold on, planet? “Maps of Land aren’t stretched at the edges,” I ask. “Land is flat, then?” It’s not the strangest thing I could have imagined, though I really should have expected it given how they called it a “plane” in the speech.

“Yes,” Heather answers. “Before you ask, no, there is no edge; if you go too far you simply end up where you started.”

“Huh,” I say, intrigued. “What’s the topology like? I mean, uh, I have no idea how to describe this without drawing and labeling a picture. If you go north off the northeast corner of a map, where do you end up? Southeast corner going north, southwest corner going north, something else?”

Heather thankfully doesn’t have to think about it very hard, which means it’s relatively common knowledge. “In the south-east corner going north.”

“Ah, connectivity of the torus, then.” I look at the sky. Definitely no other half of a torus in the sky! Not that I was expecting to see one, Land is entirely flat, there’s no inside diameter and outside diameter, so it’s not a big donut embedded in three-space, it just… is flat and wraps around. “What happens if you dig straight down,” I wonder out loud. “Do you wrap around into the sky or something?”

“No, you just come out halfway across the plane,” Heather says, because of course the answer isn’t that you get burned a crisp or crushed first. “There’ve been trade routes in the past that worked that way. Nothing right now, though, none of the stable polities are positioned for it to be economically viable.”

“That’s a shockingly grounded evaluation in the context of such weird geometry and physics,” I giggle. At some point I’ll have to sit down and crunch through the math on that, see what the geometry is like and if there’s any way can exploit it. If I’m lucky there’ll be, like, a singularity somewhere and I can track it down and use it to get infinite power or travel through time. “But that means that Land is the center of the universe, doesn’t it? I guess that’s not actually a problem if you’re in another universe,” I immediately answer my own question. “Ugh, there’re probably privileged frames of reference and junk too, aren’t there.”

All of my physics knowledge is going to be invalid. Probably also what little biology and chemistry I remember too. Good thing I’m a computer scientist!

Ahhh, mathematics, the purest field of science there is.