Good Rules For Magic

[Hiram McDaniels]

I don't mean game mechanics here, but rather in-universe rules for what magic can and can't do. Kind of like how the genie from Aladdin has restrictions on the wishes he'll grant, or how Full Metal Alchemist has the law of equivalent exchange, or how Patrick Rothfuss' Marty Stu masterpiece The Kingkiller Chronicle has the laws of sympathetic magic.

Obviously, this depends on how low/high magic you want your setting to be. D&D's base assumption is that you can accomplish anything with a high enough spell slot, while lower powered settings might either place hard limits on what magic can/can't affect or the universe just pimp slaps you for flying too close to the sun.

So far I like:

The Law of Equivalent Exchange: We all know how this works

The Law of Universal Equilibrium: Magic warps the fabric of the universe, but eventually it rights itself - therefore it can't create anything permanent.

This is mostly just a thought exercise. I'm looking for good examples of "rule magic" from games and fiction, or denners own ideas.

[DrPraetor]

Good in what sense?


Good for game balance, good for telling compelling stories or coming up with compelling characters, good for adjudicating unexpected rules outcomes...?

I like Shadowrun's conceit, that magic has to be biological in origin - but that's more a restraint on how magic can work rather than on what magic can do (which, in Shadowrun, is basically anything.)

I'm not a fan of the particular set of restrictions Ars Magica uses, which seldom come up except to protect the setting from the PCs.

[deaddmwalking]

In D&D, magic is intelligent. Like, REALLY, REALLY smart. Like smarter than any character or player. Like, impossible to fool intelligent.

That's bad.

Magic shouldn't have any governing intelligence independent of the caster/the animating force. Like having skeletons and golems possessing some form of intelligence because you bound a soul/elemental is fine - there's something running the creature. But if you look at a spell like invisibility where 'the magic' determines if you're trying to harm someone by poking at your sword or not trying to harm someone by poking at your sword, or determining if the thing you're swinging a sword at is a creature or an object, and not a creature pretending to be an object, etc.

[Ancient History]

Metamagic (i.e. magic that changes/expands parameters) is fine, and actually really useful for keeping magic versatile and viable.

Magic that affects dice rolls (adding/subtracting bonuses, creating special pools of dice, fucking with probabilities, etc.) is generally bad, as it encourages meta-gaming. This doesn't mean you can't have buffs and debuffs, but the buffs and debuffs modify attributes rather than being generic pluses. Even in Shadowrun it became almost a game to see how many bonus dice you could add to a given roll. Fucks over game balance something awful.

Shadowrun otherwise had some interesting and distinct restrictions: it split off magical ability into distinct skills (Sorcery, Conjuring, Enchanting, and depending on the edition Divining, Astral Combat, and Assensing), and doubled-down on that by giving sorcery a lot of things it could not do so as not to step into Conjuring or Enchanting's territory - see deaddmwalking's comments.

Earthdawn had something closer to D&D-style magic, where there was less distinction between skills (you could summon spirits via spell, ritual, and Discipline ability, for example), but they were much more consistent than D&D in terms of metaphysics. Having a good metaphysical basis to your magic system can make things a lot easier.

For example, if you decide there's an astral plane that is coexistent with the physical world, and PCs have access to it, that has a lot of implications, and it is important to determine how characters can and cannot interact with it.

[Hiram McDaniels]

Good in what sense?

I meant more in the narrative sense than anything else; creating internal consistency in a world of magic and fantasy.

Someone in a D&D facebook group was looking for advice on running a murder mystery themed adventure, and another poster quoted Arthur Conan Doyle: "Once you eliminate the impossible, whatever remains, no matter how improbable, MUST be the answer. That got me thinking: how can you eliminate the impossible in D&D where literally anything is possible?

Though I guess if you did manage to place limits on magic you could then extrapolate some sort of game balance from it.

I'm not a fan of the particular set of restrictions Ars Magica uses, which seldom come up except to protect the setting from the PCs.

How do you mean? Are you referring to the 4x5 magic structure?

In D&D, magic is intelligent. Like, REALLY, REALLY smart. Like smarter than any character or player. Like, impossible to fool intelligent.

That's bad.

Magic shouldn't have any governing intelligence independent of the caster/the animating force. Like having skeletons and golems possessing some form of intelligence because you bound a soul/elemental is fine - there's something running the creature. But if you look at a spell like invisibility where 'the magic' determines if you're trying to harm someone by poking at your sword or not trying to harm someone by poking at your sword, or determining if the thing you're swinging a sword at is a creature or an object, and not a creature pretending to be an object, etc.

Ehh...that kind of fits though. In the Vance stories, magic spells had a will of their own, usually intending to fulfill their purpose: fire spells wanted to burn, Illusion spells wanted to deceive, etc. In the Elric stories, magic spells mostly consisted of conjuring lesser demons to perform tasks for you.

But I do see what you mean. A fireball doesn't make any decisions; it simply goes where it's told and explodes there, yet a magic missile knows when it's being targeted at a living being as opposed to a rock or door. It should be one or the other; either spells possess intelligence or they're just a flashier version of a wrench or hammer.

For example, if you decide there's an astral plane that is coexistent with the physical world, and PCs have access to it, that has a lot of implications, and it is important to determine how characters can and cannot interact with it.

That's an interesting one. You need to cast a spell or find a portal to get there, but once you do you can visit people in their dreams? Does that mean your consciousness enters the astral plane when you're in REM sleep? Can you get there by sleepwalking?

[Stubbazubba]

I meant more in the narrative sense than anything else; creating internal consistency in a world of magic and fantasy.

Sanderson's First Law
Sanderson's Second Law
Sanderson's Third Law

Start there. Magic in narrative is, ultimately, a narrative device, and it follows the rules of all other narrative devices.

The conversion of these ideas to gaming is not straightforward, though, nor is it necessarily even desirable. A "good" magic system for a game is not necessarily the same as a "good" magic system for a story.

[Lokathor]

That's an interesting one. You need to cast a spell or find a portal to get there, but once you do you can visit people in their dreams? Does that mean your consciousness enters the astral plane when you're in REM sleep? Can you get there by sleepwalking?

In the specific case of Earthdawn/Shadowrun the Astral Plane is a conterminous plane with the material plane, and some creatures/things are "dual natured" which lets them exist in both at once, while other things are purely physical or purely astral. Magicians (normally purely physical) can even turn the dual-natured effect on and off at will, while some spirits (normally purely astral) can use a power to gain a physical body and be dual-natured.

And there's all these metaphysics about how it works and stuff.

[Username17]

I meant more in the narrative sense than anything else; creating internal consistency in a world of magic and fantasy.

Then it doesn't really matter, as long as they are simple enough that your audience can remember them and consistent enough that you don't get into a lot of arguments about how they work. You can build a narrative around any particular set of magic you happened to have. Indeed, weirder limits of magic sometimes lend themselves to some pretty cool stories.

How do you mean? Are you referring to the 4x5 magic structure?

Ars Magica's magic has two "greater limits" that are:

• 1. Magic cannot influence a pure manifestation of the Divine.
  2. Magic cannot permanently change a target's Essential Nature.

Those are fucking gibberish. But essentially they mean that magic is totally incapable of doing a thing the MC tells you that you can't do. There's no predictable limits or extents. If something can't be done it's because of interaction with properties that no one can know or agree upon. God's Will and Essential Natures are made up things that people have been having stupid fucking arguments about for thousands of years. You are not going to sort that shit out during an actual game in between the time you want to cast a spell and when you roll dice to decide what the results are supposed to be.

But really, the bottom line as far as what rules are good or bad is that the kinds of stories that can be told in different mediums are different and have different constraints. Just for starters, in a TV show a set of magic rules are good if you can work out from an event how it was achieved - while in an RPG a set of magic rules are good if you can work out from what is attempted what event will occur. That's perhaps a subtle point, but the fact that the causation arrow points the opposite direction is really fucking important in determining whether and when the magic being "open ended" is good or bad.

-Username17

[Ancient History]

Consider Dragon Ball Z.

Dragon Ball Z introduced the concept of power levels. Higher power levels became correlated with being stronger/faster/bigger blasts/better fighter. A character with sufficiently high power levels could destroy whole planets.

But there was more! Because it wasn't just "Who Has The Higher Power Level Wins." Technique was important, and strategy. Being able to hide or raise your power level was important, as was the ability to sense power levels. Transformations became very important, but also energy/stamina.

So it was really the combination of these concepts and techniques, how they interacted and defined the conflict and relationships throughout the series, which is what made it interesting and generated the real drama in the series.

Of course, power levels are bullshit. Energy/stamina is always relative, there were never hard limits in the show itself, the drama was manufactured, there were always asspulls. There was never a thing where an attack cost X energy and did Y damage in the show, because the show isn't a video game or RPG. But it worked within the context of the how; people still have bullshit arguments about power levels and who was stronger and who can beat who, and that is kinda what you want, that level of engagement and being able to engage with the material. Eventually, power levels got so utterly ridiculous, the numbers so big that they were pointless - but for a while there, you could definitely see the underlying mechanics and it worked and was cool.