"Spell resistance is also one of the limits of magic - there are spells that need consent, but other than not giving consent or physically getting out of range, or sometimes just being an inapplicable target if you're something like a huge magical rhinoceros, there's no 'resistance'."
She adopts the applicable mental attitude to consent to the spell as if it's some kind of Night effect, and doesn't even flinch when touched, although someone good at reading people would have been able to tell that took some effort.
Now her scattered, long dormant recollection of the limits of magic is coming into much sharper focus. This is very pleasant, she could really get used to this.
"It doesn't make much sense to start with the limits, actually - let me list out the laws of magic first, then the extra limits are really just edge cases.
The law of intent - only the original intent in designing the spell or ritual matters, you can't apply a ritual or spell for one thing to something else. Sometimes you will manage a ritual with a potential range of targets, or some small flexibility of effect, especially if you codify it, but there's nothing to be found by experimentally applying things to other things, it's all laid out in the ritual text.
Oh - codify means, we can do experiments that create an 'arcane projection' which is a kind of preliminary, limited ritual which may only work once, and then with an awful lot more research that can become a 'ritual text', which is generally cheaper and can be used repeatedly by other people.
The law of presence - it's much easier to affect something that's directly present, there are ways to follow magical connections to reach further away but the effects you can have there are much more diffuse.
The law of dominion - if you have authority over something, that's a magical connection and you can be used to affect that thing - so a ritual on me could affect Foundhome, especially the mana site there as that's magically salient, or a ritual on a general could affect their army. The Imperial Regio in Anvil can affect any region of the Empire, an egergore can be used to affect their whole nation although that is generally prohibitively expensive.
The law of bonds - that basic spell I mentioned, create bond, can link people to items, or people who are already linked through an egergore to each other, and those bonds are also a valid conduit for magical effects.
The law of scale - every magical effect has a natural scale, it's not much cheaper and sometimes impossible to make a smaller version of an effect that's already near its optimal scale, and becomes rapidly more expensive or impossible to exceed it.
The law of transience - magical effects also have a natural duration, a season for enchantments, a year for curses, much shorter for spells. Ilium can overcome this but it's very rare and you need a lot of it. This also applies to our enchanted items, they naturally fade in a year, although potions last indefinitely.
The law of synergy - it's easier to add more targets to a ritual than to make it longer or more powerful.
The law of boundaries - there are natural geographical boundaries to the world that magic obeys, they can't easily be redefined, anything that affects a wide area does so based on them.
The law of essence - you can't affect the fundamental nature of something. This is a bit difficult to explain, but the most common related result is that once an injury has settled into someone's self-image, you can no longer heal it with magic, even if it would usually work. Especially weird things have to be called up from the Realms, generally with a specific Eternal providing them, rather than just conjured.
There are the limits I've already mentioned - death, resistance to magic - we can't be entirely immune to swords either, although the effects can be mitigated - compulsions, emotional effects are common but they make you feel a certain way rather than do a certain thing, that includes no absolute truth magic.
Other limits, true invisibility - magic can distract people and improve stealth and call up concealing mists but not actually make someone vanish entirely. Silence - even our paralysis magic leaves the person capable of speaking or screaming. Complex territory effects - anything that affects a whole territory is broad and indiscriminate, it can't intrinsically give your side an advantage. Maps, if you want to affect somewhere far away you don't have dominion over you can get some passive effects through a map, like divinations, but nothing else and nothing if you don't have a map.
There are some weirder cases like what you can do with lineage or an egergore bond but I don't see how those would come up."
Oh. Possibly that was quite a lot of very dense talking. It seemed a lot less difficult to think of what to say, under the effects of the spell.
"Did you need me to repeat any of that?" she asks.