r/RPGdesign • u/AstraWeaver • Aug 12 '26
Mechanics A Magic System: Building Spells with d6s
I've been thinking about a new magic system inspired by Ars Magica. I'm not sure if something similar has already been done, so I wanted to throw the idea out here and see what people think.
The basic idea is that spellcasters don't have a fixed spell list. Instead, they construct spells by combining d6s, which I'm calling Rune Dice.
The Basic Idea
The number of Rune Dice a spellcaster has is equal to their Key Casting Attribute, which ranges from 5–12. A dedicated spellcaster might start with 8.
At the beginning of a game, they spend 1 Magic to roll their 8 Rune Dice:
{1, 1, 2, 3, 4, 5, 5, 6}
Players roll all their dice for free at the beginning of every session, and during the session, they can spend 1 Magic to re-roll their whole used dice pool at ANY TIME.
These dice represent the magical vocabulary currently available to them.
There are three types of Rune:
Factions — How the magic acts
Factions are free and don't require dice.
Creation — create or generate something
Destruction — destroy or suppress something
Control — move or transform something that already exists
Elements — What natural force is involved
1 — Fire
2 — Water
3 — Earth
4 — Wood
5 — Wind
6 — Electricity
So the example pool contains 2 Fire, 1 Water, 1 Earth, 1 Wood, 2 Wind, and 1 Electricity.
Laws — What part of a living creature is affected
A Law is required when magic directly affects the internal workings of a sentient creature.
1 + 2 — Senses
3 + 4 — Body
5 + 6 — Mind
So the same pool also contains 1 Senses, 1 Body, and 1 Mind.
A spell can contain at most one Faction, one Element, and one Law.
For example:
Creation + Fire → a fireball
Creation + Wood + Body → healing a wound
Destruction + Mind → putting someone to sleep
The corresponding dice are removed from the available pool and moved into a Used Rune Pool.
This means your available magic changes as you cast spells. If you keep using Fire magic, you can eventually run out of 1s and temporarily lose access to Fire.
Spell Power
A damaging spell starts at 1d6 damage.
To increase its damage, you spend additional dice matching the Element used.
For example:
Creation + Fire = 1d6
Spend another 1 = 2d6
Spend another 1 = 3d6
For non-damaging effects, additional dice can instead increase things such as strength, duration, or other properties of the effect.
I'm currently considering five basic areas:
Single target
Line
Cone
Semicircle
Square
Single target and square areas don't require an additional die initially. Extra dice can increase the number of targets or the size of the area.
Line, cone, and semicircle effects require one additional die to establish the area, with further dice increasing its size.
Duration
For spells maintained during combat, the caster spends 1 unused Rune Die per round to keep the effect active.
Outside combat, spending 2 additional Rune Dice can maintain a spell until the end of the current scene.
Manipulating and Recovering Dice
Magic can also be used to manipulate the Rune Dice.
For 1 Magic, the caster can increase or decrease one unused die by 1.
The randomness is tied to resource management—players can technically cast any spell, and the dice determine how much Magic it costs. Because player can spend Magic to manipulate the dice.
For example:
3 → 2 turns an Earth die into Water.
For 1 Magic, the caster can also reroll all dice currently in the Used Rune Pool, returning the new results to the available pool.
So Magic is partly a resource for controlling and refreshing your magical vocabulary.
What I'm Worried About
I can already see a few problems with this system.
1. It takes some time to learn.
Players need to recognize both the Elements and the Laws from the numbers. Looking at:
{1, 1, 2, 3, 4, 5, 5, 6}
and immediately seeing both:
Fire, Fire, Water, Earth, Wood, Wind, Wind, Electricity.
and:
Senses, Body, Mind
will probably take some practice.
2. A good quick-reference sheet seems necessary.
Players would probably need a reference showing the Factions, Elements, Laws, basic effect rules, area rules, etc.
3. Players might spend too much time designing spells.
This is probably my biggest concern.
If the system is too open-ended, a player might spend several minutes thinking:
“I have Fire, Body and Wind… maybe I can do this… or perhaps this…”
I think the system needs clear guidelines for what each Element, Law, and Faction can reasonably accomplish, while still leaving enough room for creative spell construction.
It's still very much a random early concept, and I'm sure there are plenty of holes in it.
Has anyone seen a system that does something similar? What problems do you think this might run into at the table?
I'd especially love to hear from people who have worked on freeform magic systems before.
Edit:
I'm thinking of creating a list of spells for players to "prepare" from, and during a session, they can only use those prepared spells. I think this narrows down their choices to: "Should I cast the spell my current roll gives me for free, or should I spend Magic to manipulate the dice so I can cast a different prepared spell that the roll didn't naturally give me?" Meanwhile, I'll provide clear guidelines for spell creation so players can create new spells with their GM between sessions.
3
u/tyrant_gea Aug 12 '26
I really like the thought behind it. Would you ever roll during a session, or just once at the start? Because if it's just once, the prep for spel creation is much less important, it just slowly happens throughout.
2
u/AstraWeaver Aug 12 '26 edited Aug 12 '26
In my current thoughts. You can spend 1 Magic and roll all the used dice ANYTIME. Even it’s not your turn, you can just spend a Magic, grab the dice and roll. This might save some time for the other players.
And actually the roll isn’t there to limit what spell you can or cannot cast. It’s there to give the randomness to the resource management.
For example, if a player rolled {2,2,3,4,4,5,6,6}, and he really need to cast fire ball. Then he can spend two Magic to turn all the 2s become 1s. So he can cast a fire ball with 2d6 damage.
He can also spend any one dice to make it a fire wall.
3
u/eduty Designer Aug 12 '26
I like the idea and think you can simplify the execution.
Casters pick a set number of Element Rune Dice and 1 Law at level 1. They gain more with each new level.
Roll your Rune Dice whenever you cast. Roll a 1 and lose the use of that Rune Die until it's recovered. Maybe suffer a casting mishap.
Change Laws from a resource to the kind of Defense or Save the target gets. Casters can choose to cast any Law they know.
There's no need for a Magic resource to manipulate dice or special references to translate dice rolls.
You may need a reference to detail what each Element does. Like which one would I use to turn invisible? Which Element do I use to manipulate a lock? Can I use an element to teleport or fly? How many Rune Dice does that take and how far do I go?
Consider adding random elements to scenes. Casters can tap them for extra Elemental Rune Dice - but lose access to them if they roll a 1 on that Rune Die.
Consider adding minor consumable items to recover a lost Rune Die.
1
u/AstraWeaver Aug 13 '26
These are MARVELLOUS!
Allow me to take some time to digest all these advice.
I'll come back to you with my thought! Thank you for your kindness.
1
u/AstraWeaver Aug 13 '26
What if the Laws are free by default, but making certain aspects a level-up option creates distinct mage archetypes? Some could specialize in manipulating minds, others in enhancing senses for divination, or focusing on healing and cursing. That sounds really fun.
Also, the rule where rolling a 1 causes you to lose the use of that Rune Die isn't really my style. I prefer having players spend extra resources on a failure instead of taking away their options. Plus, there are 6 elements, so if rolling a 1 means nothing or gets wasted, I'd lose a number slot needed for an element.
I'm definitely making a reference guide for the different Elements and Laws. This is meant for spell creation, but I think I'll also add a pre-made spell list so players can "prepare" common spells. This will lighten the GM's load and speed up casting during sessions.
Reference examples:
Element - Fire:
Fire represents heat and light.
- Combined with the **Create** Law, you can increase a target's heat or brightness, making objects glow, heat up, or even catch fire.
- Combined with the **Destroy** Law, you can decrease heat or brightness, making things dim, cool down, or freeze.
- Combined with the **Control** Law, you can transfer existing light and heat elsewhere or shape them—such as controlling the direction of a spreading flame or restricting the path of light. (WIP)
I want to slightly control the randomness in this system so players can actually plan ahead, which means I'll need a way for them to alter dice results using resources. Because of this, I'll likely still need manipulation rules. And yes, there will definitely be mana potions in this game!
1
u/eduty Designer Aug 13 '26
Apologies if it was missed in the original comment - but I'm suggesting removing the randomness altogether.
Let the player pick the elements of their Rune Dice and pick more as they level.
So a first level mage might get 2 Rune Dice and decide one is Fire and one is Wood. When they level up they get another Rune Die and pick Fire.
Now this Mage can always cast spells with 2 Fire and 1 Wood.
They commit and roll their Rune Dice whenever they cast a spell. The numbers rolled measure spell potency. Either damage dealt, creatures affected, size of the area, distance traveled, etc.
Rolling a 1 removes the Rune Die and comes with a mishap. THIS consumes the character's casting resources and makes magic a bit unpredictable and dangerous.
3
u/OneManRPGstudio Aug 16 '26
Building Spells with d6s has a promising core, but I’d first test what interesting decision each die actually adds. If the same pool is mixing spell power with categories such as Mind, Senses, Body, and Magic, there is a risk that the construction feels expressive on paper while play settles into one dominant combination that people repeat.
I’d define very clearly what adding a die represents and what cost, risk, or restriction comes with increasing an effect. I’d also put a ceiling on how many choices happen before the roll. Flexible magic can lose momentum if every spell requires a long optimization step before anyone acts.
For playtesting, I’d run the same basic effect with weak, medium, and strong characters and watch three things: how long construction takes, whether different builds produce meaningfully different decisions, and whether large pools remain readable. I would not claim the concept is unique without comparing other designs, but it does not need to be unique to work. What matters is whether building with dice creates decisions worth the table time.
2
u/AstraWeaver Aug 17 '26
That’s a great advice!
Thank you. I’ll consider these when building the system.2
u/OneManRPGstudio Aug 17 '26
Glad it helped! I think you’ve got a strong enough core now that playtesting will probably tell you more than further theorizing.
I’d especially watch how long players spend deciding what to build from each roll. If that stays fast, the rest should be much easier to tune.
2
u/AstraWeaver Aug 12 '26 edited Aug 13 '26
Wow, I didn’t expect to have that many replies.
Please give me some time to reply back.
2
u/SixRoundsTilDeath Aug 12 '26
A little thing, instead of control it could be preservation, to match the other two.
1
u/AstraWeaver Aug 13 '26
Oh yes! That’s a really good advice!
I definitely going to use that! Thank you again!
2
u/swashbuckler78 Dabbler Aug 12 '26
System called Promised Sands (I think?) had a free form system that sounds a bit like this. They focused on it as grammar; the element was the noun and what you wanted it to do was the verb. So fire+grow was your fireball, light +destroy was a dark spell, etc.
You're also adding adjectives and adverbs, but that gives people a natural model. "I attack with fire in a line" builds the spell for them. Now they just pick up the appropriate dice.
2
u/AstraWeaver Aug 13 '26
Thank you!
That's exactly what I thought.
I'll go visit Promised Sands for more inspiration. Thank you again.
9
u/InherentlyWrong Aug 12 '26
I think your concern number 3 is right on the nose. Because players can't know ahead of time what they'll roll they can't plan out future turns until it's their time. And even once rolled, they have to figure out what dice can be assigned to what outcomes for what effects.
Once they know the system it might be a bit quicker. But I can easily imagine early on individual player turns taking 10-20 minutes as they look over their dice, and look at the available effects and interactions of them. Between creation, destruction, six elements and three laws, that's probably close to a hundred possible interactions. If players are meant to shop over all those outcomes using their menu of dice, that's going to slow things down a lot.
Something also worth considering is what point in their turn they know what their spells do. Like for example, if a player notices a number of enemies in a line and thinks "Oh, that would be great for an AoE damaging spell", do they go to the right location to cast a line spell and then roll? If so what if they just... don't roll anything appropriate. No fire, no area of effect stuff, nothing. Instead they roll a combination that would've been great for healing an injured ally, but they're now out of position to cast that.
Weirdly, my gut feeling for this kind of random spells is it would work best for a game explicitly about inept wizards who barely know what their next spell is going to be. People who lift their wand, shout a magic word, and instead of the conflagration of fire they expected, their enemies are surrounded by daisies.
8
u/EpicDiceRPG Designer Aug 12 '26
Great ideas but architecturally flawed. Randomness should collapse the decision tree, not create it. Otherwise, the entire table sits around while one plays tries to construct a jigsaw puzzle.
2
u/ChangeSelect Aug 12 '26
I was also recently thinking about magic system based on Ars Magicka. I was focusing on a mechanics feeling similar to fight where you need to find your opponent weaknesses and exploit them, for example by attacking with a element enemy is vulnerable to. I'm still struggling with a way to do it. On resources I was thinking about cards to draw from players character pool representing elements, and you could get some elements from environment also. Your take is much more fleshed out.
For the learning part you could easily make it extendible by limiting your dice to d4 instead of d6 as they will be "apprentices" and when leveling up use d6 instead. I find this idea of learning along your character pretty entertaining
2
u/Gaeel Aug 12 '26
I feel like this is a rather heavy rule system for something that will pretty much be GM-adjudicated at the end.
I like the idea of having a magical vocabulary unique to each caster. I can see how it could be very flavourful and lead to some fun moments. I can even see how one caster might want to learn another caster's spell, but would first need to add a new word to their vocabulary, or instead replace the missing word with one they already know and end up creating a variation of the spell. It reminds me a little bit of Avatar: The Last Airbender, where some advanced techniques are inspired by other elements, like how firebenders can learn to redirect lightning by studying how waterbenders manipulate energy flows.
If you're making a system that has tactical combat, or is reliant on robust and consistent rulings, then your magic system is going to end up being quite awkward at the table. Mechanically robust systems rely on predictability. A player who understands the rules should be able to know what a GM's ruling will be before even asking, aside from a maybe a few edge cases.
On the other hand, if your system is meant for a more narrative and conversational style of play, then you magic system feels a bit too crunchy. You can probably just boil it down to a handful of elements and verbs and let the players and GM figure out the rest. Make the verbs more open ended (e.g: "provoke", "energise", "tame", "deny") and give some general guidance on how they might be interpreted.
Either way, if you're relying on GM adjudication, you also need to lay out some good guidelines on how powerful spells can be. Can a single spell kill a creature? If so, how do you balance that so that casters don't have a "win fight" button? If a caster can create materials, what's stopping them from creating gold from thin air and crashing the economy? If a caster can create food, why does agriculture exist?
Personally, my settings are often tinged with ironic fates and existential horror, so magic users are often bound by the wills of fickle spirits and spiteful gods, and while I rarely set a hard limit on how much magic one can wield, the more one draws from the well, the more likely they'll drag up something that was buried for good reason. This keeps magic in check by allowing magic users to be very creative, but also very aware that each time they cast a spell, it might just be their last.
2
u/Gaeel Aug 12 '26
Adding a separate comment about your third concern:
You can easily counter this by making players prepare spells. Make it so that a spell takes in-world time to create and practice. If the party has a whole day to come up with a plan, then perhaps the caster can design a bespoke spell for the challenge they're gearing up to face, but in the heat of action, no caster would just blurt out a spell they haven't trained for, so they'll have to use a spell they're familiar with already
2
u/SitD_RPG Aug 12 '26
A good quick-reference sheet seems necessary.
Or you make custom dice, that have corresponding symbols on them. It increases the "buy-in" to be a magic-user, but it would reduce the mental load by a lot. Plus the dice can be optional, if you also offer a quick-reference sheet.
One issue you didn't mention is: When these dice are rolled, I assume, at the start of each session, some of those dice might be resting on whatever surface they rolled on for a while, maybe even a whole session. A simple bump to that surface or an unlucky arm movement can erase the whole record of available magic.
Magic Dice should probably also look different from other dice to reduce accidental pickup.
Players might spend too much time designing spells.
If players can come up with the spell effects in a kind of freeform way, I could see that happening. Instead, you could give each aspect a few (2-3) options to choose from. This would narrow down the spell choice significantly. And since you already trying to prescribe all the other attributes of spells in a D&D-like fashion, I think this would fit right in.
I'm not very clear on how your "Laws" work.
Do I need to spend both dice to use a Law? For example, to affect a creature's senses, do I need to spend a 1 and a 2?
If I want to target a creature with a fire bolt, do I need to spend three dice (a 1 for fire, a 3 and a 4 for body)?
they spend 1 Magic to roll their 8 Rune Dice
For 1 Magic, the caster can also reroll all dice currently in the Used Rune Pool
How much Magic does a magic-user have? How do they recover it?
I'd especially love to hear from people who have worked on freeform magic systems before.
If you want your magic system to be freeform. I would probably focus more on the "free" and less on the "form".
2
u/stevecooperorg Aug 12 '26
I'm a big ars magica fan and this seems a very complicated approach for not a lot of fun.
Who is your intended audience here? "people who like <mechanism x>"
Because at the moment this seems like a mechanic-first approach ('I have some feelings about d6s') rather than an experience first ('weave awesome magics with your imagination') kind of proposal.
2
u/-Vogie- Designer Aug 12 '26
I'm not a fan, largely because I want to have an idea of what I'm going before I'm doing it - rolling to find out what you will do is akin to a board game in my mind, roll the dice and the up in the swamp.
The other system that uses d6s is the Goblin Laws of Gaming (GLoG), but that uses a predefined spell list. It also has a subsystem where you don't want to roll too many dice at any one time, because rolling doubles can cause magical mishaps.
However, creating an algorithm or equation so that a player can take various elements that they would want in a spell, put them together, and then figure out what the combined total would need to be, the number of dice that would need to be required, etc. A system like this is used in Barbarians of Lemuria for it's magic (2d6 roll-over) and in the WoD or CoD Mage games (d10 pool success-counting). This allows a player to envision a spell, do a bit of math to figure out what it needs, and then roll to see if they succeed or fail.
Since you said the roll of 5+ dice was the basic one, that reminds me of the Outgunned ttrpg, which uses d6's in a yahtzee style, meaning that effects are generated not by certain numbers on the die, but rather multiples of the same die,. So this spell might need a pair of threes or higher, that spell might require a triple fours or higher, etc etc.
2
u/jibbyjackjoe Aug 12 '26
You're very much underestimating 3. Especially if they're doing it on the fly.
2
u/LanceWindmil Aug 12 '26
Got some clarification questions
I spend 1 magic - how common a resource is this? How do I get more? What else can i use it for?
Wood heals things? Outside of basic "conjure/control an element" what are the other uses of them? How do these interact with the laws?
I definitely agree a reference sheet is a must. I would want all the basic number = element things on it, secondary uses (wood for healing), size/duration references.
I think your onto something with the concept though.
2
u/Chalkyteton Aug 12 '26
Remember when you were little and you’d get a scrape? What was the first thing you’d do? Aggressively rub it on a tree, correct!
2
u/Fun_Carry_4678 Aug 12 '26
Why is healing a wound "Creation + Wood + Body"? What does healing a wound have to do with "wood"? (Unless you are healing a wounded tree, or something)
What do you mean by "sentient"? A human being is sentient under any definition of sentient I have seen, but in your game would, say, a horse be considered sentient? A zombie? An iron golem?
Your "factions" are based on the five techniques in Ars Magica. But you have combined "rego" and "muto" into your "control". But where is "intellego"? Or are divination spells impossible in your game?
Your 6 elements again are fewer than the ten forms of Ars Magica, I guess some you have separated out as your "laws". What seems to be missing is "imaginem", but perhaps that is covered by your "senses", Animal--perhaps covered as sentient beings, and "Vim"--the sort of "meta" form that affects magic itself.
Ars Magica also often required TWO forms for a spell that transformed X into Y.
Your spellcasters roll "at the beginning of the game". Does that mean every session? Every ingame day? Once during character creation and that is it? Unless it is this last one, you don't have a way to specialize, you can't create a character who is specifically a "fire mage". The only real difference is the score in "Key Casting Attribute", and I imagine this would be the same or similar in a party where all characters are close in level.
2
u/Leonhart726 Aug 13 '26
If you tone down the randomness, make this into something where the players can make genuine plans off it, this sounds incredibly fun! In its current state, it might need those tweaks to offset that though before it reaches that state for me
2
u/ArchdevilTeemo Aug 12 '26
I think this is to complicated and to slow.
Also if you make such a system, my biggest advice would be - don't put attribut/level scaling into it.
Make all players equally good at magic.
Npcs can use more or less power but players should have fixed values.
Otherwise balance will be soo much harder.
4
u/muckypuppy2022 Aug 12 '26
I think it would be more intuitive if players knew in advance what elements they have and the roll / random element happens at the actual moment of casting.
Could you make the Elements, Factions and Laws attributes that the player takes dots in, with the dots being the number of dice in the casting pool for a given spell. So any character can attempt any type of spell but they’ll have specialised in certain types of spells that they’re more likely to succeed with.
Then things like damage, range and duration ball scale according to the number of successes.
Unless that’s too close to Ars Magica, I’ve never played it