June 13, 2024

Musings on RPG Magic Systems

Brant Guillory, 17 February 2020

Everyone that’s grown up in the fantasy RPG world knows how D&D’s “Vancian” magic works, and over almost 40 years of gaming, my experience is that virtually everyone hates it.  There’ve been a variety of replacements introduced over the years, from spell points to the DD4e at-will/encounter/daily powers to skill-based magic.  Stripping back from execution to concept, however, there are always a few considerations that need to be framed before moving forward with whatever way in which “magic” would appear in the game world. These underlying concepts are the building blocks which define virtually any magic system.

These are four key definitions that need to be laid down under a common framework in order to build a specific type of magic system.wiz

  • Effect – what are we trying to accomplish?
  • Magnitude – how wide-ranging is the effect?
  • Trigger – what causes the effect to ‘go’?
  • Limitation – how do we set a threshold on what a specific caster can accomplish?

Let’s look at each of these in greater detail:

Effect:  What are we trying to accomplish?

Depending on the world you’re in, “magic” is defined in different ways, but ultimately it comes down to somehow “changing reality”: you’re creating fire without the usual fuel/heat/air triumvirate, or changing the way light refracts to make someone invisible.  Without trying to define the detailed ways in which you’re bending physics, you need to identify the effect you’re after.

The old Duel RPG defined effects relative to player stats. The effect you defined would either raise or lower your someone’s character stats, raise or lower someone’s character health, or move someone around.  This is a very ‘mechanical’ way of defining the effects, and leaves it up to the players to play out the ways in which is happens.

The Marvel universe never really explains the way that Wanda’s “hex” power works, and the MCU is even more vague about it than the comics.  But the effects are clear to see in the way she alters reality to move air around, or blast enemies.

Magnitude:  How wide-ranging is the effect?

Almost every 1st-level wizard has cast a sleep spell on a kobold watchman to sneak through the back door to the dungeon.  But ultimately, you put someone to sleep, and that’s not terribly different than what Maleficent did to Sleeping Beauty’s kingdom.  Similarly, the smoldering charcoal-briquet-sized ball of flame tossed into a haystack to let the sneak out of the bar brawl is still a “fireball” but it’s just not the meteor-sized explosion being thrown at the castle wall to breach their defenses.

Trigger:  What causes the effect to go?

In the Magicians books & TV show, there’s a combination of hand-and-finger motions, and spoken word.  In Edding’s Belgariad books, it’s “The Will and The Word.”  The aforementioned Maleficent built a trigger into a spinning needle.  The twisting and tapping of the titular bedknob in Bedknobs and Broomsticks starts the bed a-flying.  More complex/strict readings of 1e/2e AD&D included a variety of “spell components” that included physical pre-requisites to be met before the spell would trigger.  It could be reading a scroll, rubbing a lamp, or rotating a ring on your finger. Something needs to make stuff happen.

Limitation:  How do we set a threshold on what a specific caster can accomplish?

There’s not an unlimited supply of magic floating around out there.  Asprin’s Myth-adventures have casters tap into force lines to make things happen, so if you’re not near a power source, then there’s no magic.  Snape/Quirrell have to maintain eye contact with Harry Potter when causing his broom to fly awry during that initial Quidditch match in the first movie.  What are the bounds within which our magician must operate?


As spellcasters become more powerful, the range of effects they can create might broaden, or the magnitude of their effects could expand, while also lowering some of their limitations.

How those game effects are created, defined, and implemented are the purview of the rules of the game, and the source of so many internet flame wars (how dideveryone argue about what was the “best” game back in the 80s, anyway?)

DD4e changes magnitude based on the level of the spellcaster, and limits the usage of the spells by defining them as at-will/encounter/daily.  Ars Magica relies on players to create their own spells on-the-fly with their ‘noun-verb’ specifications.  Rolemaster worked with spell points to limit the amount of magic in a particular day.  There’s no “right” or “wrong” answer.

Is the game high- or low-magic?  How powerful is magic in your game?  How common is it?  How easy is it to learn?  Do the players want a crunchier, procedure-driven game with detailed steps for each action?  Or are they less rigorous in their adjudication and willing to forgo the mathematical details?  How narrative do you expect the players to be as they describe their magical acts?  All of these help determine the best ‘fit’ in the magic system for a particular game.


There are a variety of considerations that need to be addressed when poking around within an RPG magic system.  Answering these inquiries won’t solve every quandary in designing the perfect magic system for the game, but they are the basic building-block descriptors that should be answerable in any magic-based setting, whether based on The Magicians or The Mabinogian.  Bending reality can take on a variety of game effects, but the range of effects should be bound, at a minimum, by these for standards.

Thanks for reading!  We’d love to have your feedback either in the comment area below, or in our discussion forum.  You can also find us on Facebook, Twitter, and YouTube

Brant G

Editor-in-chief at Armchair Dragoons

View all posts by Brant G →

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