I need help simplifying a magic system

Hi! I went back to redesign my old fantasy heartbreaker and wanted to make magic somewhat interesting to both roleplay and crunch a bit. So far I’ve got this:

System would use d20+bonuses (from 1 to 6 top), important stats for casters are WILL, and maybe CONSTITUTION or INTELLIGENCE (I’ll explain later)

Now, there’s no starting spell list. Instead casters research their spells and then make a list. The research basically consists on figuring an answer for three questions:
-From where does the power come from? If it’s internal, the value will always come from the caster’s WILL, but she will spent a point of CONSTITUTION each time she uses it (recovered on a rest). If it comes from an item, it gets a fixed value too, and an amount of charges. If it comes from an enviromental source, the caster either uses the value 1 or rolls a d6 to see how much power she can get from it. If the roll goes above her WILL, the magic goes out of her control, meaning the GM changes a variable from the spell at random.
The power can even be stolen from another living being by succeeding a WILL check. The value then is equal to that being’s WILL value and that being loses a CON point.

How is the spell triggered / controlled? Just explain what does your character do. It should be a somewhat obvious gesture, with either words, runes, material spent, a focus, etc. The thing here is that it can be interupted.

What is the effect? Here come the variables defined for the spell (and the part where I’ve got more trouble with). Here the caster divides the power between all/most of them or leaves some to the default. The power can be directly pour into Damage, increase the Range fromTouch to Close and then to Far (+1 point for each step). It can increase by 1 per opponent affected or area affected if it affects only the enviroment. Duration can be increased from instantaneous to check (a failed check ends it) to whole scene. If effect is a buff/debuff the power goes up by each point of bonus or penalty added, except that this magic can’t modify the WILL value of any being.

The spell still needs to be aimed and cast against the target, so there’s always a d20+PERCEPTION check to hit anything with it. However, anything that gives the caster a link to their target counts as an additional +2 bonus to hit (like a personal object, their true name, blood, etc).

I like the direction this is going but I do want to make it simpler. Also, I see potential for breaking the game here despite my best intentions. Like, if power sources can be multiple (it makes sense to carry an item, use a ley line and your own intter power to fuel a spell) or spells with additional duration can be cast and have their effects piled up. I’m still unsure to limit things a bit more or just simplify it and call it a day.

Without going too far into the design, I wanted to ask something about an assumption:

Also, I see potential for breaking the game here despite my best intentions. Like, if power sources can be multiple (it makes sense to carry an item, use a ley line and your own intter power to fuel a spell) or spells with additional duration can be cast and have their effects piled up.

If the players arranged all that, I think they’ve earned in both the mechanical and narrative senses the right to “break” magic. Magic is already broken physics, yeah? And this exact formula of objects and locations and Voltron-ing powers is how often we get to see the Big Bads (and sometimes the Big Goods) in media getting buck wild with magic.

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That’s another thing I’m not so sure about yet. I mean, yes, I also enjoy players breaking the system once in a while and if the game didn’t have anything else but spellcasters I’d say that things would still be balanced. Also, whatever the PCs can do, can be done by the BBEG anyway.

But if I want to include other classes I’d have to give those a chance to break the game in different ways. Then I’d have to balance for multiclassing and such. Next thing would be that I’ll have to add HP on top of the CON stat just to make characters last longer against casters. Hopefully it won’t get that far.

I just noticed I can add Summoners using the same mechanic with a couple changes. Usually these tend to break the game by giving the PC more actions each turn and the ability to be in more places at once, but using a more PbtA approach this gets automatically balanced, so no prob there. Spellcasting failure for summoners goes around getting summoned to the monster realm instead of summoning it, failing to control it or releasing something dangerous upon their own world.

Divine casters may be more straightforward here, as their power comes from a god associated to a single concept, the caster prays for it and possible power buffs are if the area is consecrated, related to their god concept or if she has a relic. The effect is limited to the concept. It may require for the caster to accumulate Favor by doing things that call the attention of their god.

Streamlining things might be possible if looking at all this from another point of view, but I can’t put the finger where to start from.

I have a couple thoughts on how you can keep this simple:

1- drop the middle step of determining how the spell is triggered. It’s not often going to be important of its hand motions or ancient words spoken aloud; just let your players know that it can always be interrupted.

2- don’t restrict your players to what they can or can’t do, that’s just extra complications. They’ll them magic can do anything and find out what that means during play. This is how Whitehack works: the player States the effect they want, the GM decides how much that would cost, then they negotiate to find a effect & cost which they are both happy with. It works great.


Exactly, and I didn’t want to jump into anything prescriptive off the bat.

Our home game has free form but self-balancing magic, which really makes us think before going for the overpowered option. The first part is that any player with a spare magic point can channel power through a character’s Heart/Body/Mind - but that’s rough because human bodies aren’t built for that. Sure, you punched through that bulletproof glass but now your bones are creaking and muscles are exhausted and there’s a shard stuck in your arm.

Even for characters who can direct magic through their aura (player has spent several XP to add a magic colour to them), sparing their bodies from the worst impacts, there is an assumption of “Magic, but absent secondary powers.” If you throw a fireball, it doesn’t wait to get hot once it’s a safe distance from you - it’s a thousand degrees, at arms length. If you open a portal to avoid a door, something might spill out from the adjacent-11-dimensional-spaces just outside our reality. How do you dissipate the energy from the sword blow your Shield spell blocked?

Anyway, in a Trad-er sense, this magic would have direct logical consequences in similar proportion. Maybe you agree on how many points of effect it is causing, and point that back at the character’s stats. Temporary penalties, Health, status ailments, or even permanent decreases to base stats. That sort of thing. Bring down a meteor, sure, but that’s incredibly taxing and there’s no way to direct it to a spot far enough afield to ensure your safety.

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I would look at the “from whence does the power come?” paragraphs for ways to collapse exceptions into more consistent behavior, or at least an easier rule of thumb. I had to read that first paragraph multiple times before deciding “I would not want to play a spell caster in this game” (and I almost always want to play a spell caster).

Edit to add: Sorry, my comment reads as unintentionally negative and not very helpful to me in retrospect. A more helpful way to say what I mean, I hope, is that you can simplify at this step by reducing the number of either/or (or if/then) statements required reach time someone casts, and by limiting each casting to a single roll per person. I dug how the choice to draw upon different sources worked in Dark Sun, though, and would be interested to see another take on it from a different sort of setting.

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Some good advice I got on developing mechanics was, start with the simplest mechanic that is still recognizable as the system you are designing. Add one feature that gives the complexity, atmosphere, etc that you are looking for. Ask yourself if that is worth the extra mental load for the player. Then go on to the next feature. It’s helped me question what I’m really trying to do when I develop a mechanic.


All right, thanks for the feedback! Been thinking it a bit more and went for a PbtA approach this time. It still starts with one question:

Where does the power come from?
Like, if there’s a source around, that’s it. Then the player rolls d20+appropiate bonus (might be a different one depending on the source) to see how everything goes:
Less than the difficulty, the GM chooses two, three on a critical failure. On a tie the spell effect goes as planned but GM choses one and the player another. Above the DC, player chooses two, and none on a natural 20.

-Caster is affected by the spell in a negative way: if it’s a buff the challenge gets the same buff, if it’s damage the caster suffers the same damage as well.
-Caster will need to concentrate another turn to cast the spell
-Power goes out of control from the source 1d6 random targets in the area get raw damage from it.
-The power used awakens as a sentient creature.
-Power is used up, you can’t use this source for the rest of the scene.
-Someone around is affected in an unexpected way, Everyone in the area rolls their spell resistance or just a d20+will if they don’t have one. The lowest roll (ties don’t apply, both get the effect) is affected. In a positive way if the result is pair (enhancement or inmunity) in a negative way if it’s odd (debilitating mutation or inability to mantain a shape) GM decides which and how. On a natural 1 or 2 the effects become permanent, otherwise they last for the scene duration.

I’ve definitely got to add more interesting options to this list. Plot twist: the player won’t know what’s exactly in this list until it happens to them. So, she can choose what to avoid only when she’s experienced enough.

Using material, somatic and vocal elements as well as the name or things that belong to your target, etc, may still lower the DC of the spell. The more precise or reality-warping the effect, the higher it becomes, so altering the laws of probability may be easier than bringing things to life. This totally needs a list of examples as well.