Dangerous Magic


Homebrew and House Rules


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So, since 2010, I've been playing in a Warhammer Fantasy Role-Play 2nd Edition game, and I've really fallen in love with the magic system. So, I've been working on applying the spirit of that magic system to Pathfinder. The following is a link to my current version. Please note that this is a prototype and has yet to be play-tested.

Dangerous Magic

I'd really appreciate any feedback! Thanks in advance!


So if the 2d20's (Control and Power) together are added to see if the result beats the spell’s Power DC (so then the spell is cast)?

Very interesting idea.


Not exactly. When you roll the 2d20, the die that rolls higher is the power die. The result of that die, plus a bonus granted by x number of caster levels, must beat the spell's Power DC in order to cast. This result can be further augmented by taking a channeling move action prior to casting the spell, which allow the caster to add their casting stat mod to the roll.

The die that rolls lower becomes the control die. This die must beat the spell's control number (spell level + 1) in order to avoid adverse side effects of casting the spell. It has no bearing on the actual casting of the spell.

Thanks for the feedback! Any suggestions on how I can explain the dice mechanic more clearly, to avoid future confusion?


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Well, I got the Control Die.
I think you edited it, it now reads, "if result of Power die", before it said if the result beat the DC.

Which is why I was curious which you meant before.

The wild magic does fit how Warhammer was like.


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Starbuck_II wrote:

Well, I got the Control Die.

I think you edited it, it now reads, "if result of Power die", before it said if the result beat the DC.

Which is why I was curious which you meant before.

The wild magic does fit how Warhammer was like.

I was hoping that edit was enough to clear things up!


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Good to see some free dangerously magickin' stuff out there. ;)


Some initial questions/comments:

1. It looks like the Power die is essentially doing the same thing as a Concentration check to cast defensively, except it applies all the time. The obvious question, then, is "What happens when I cast defensively?" Do you make both checks (clunky and a drag on play time)? Do you make the Power check at a penalty?

2. I know there are logical reasons I should dislike adding randomness like wild surge tables, but they're so daggone fun, to me, that I can't bring myself to condemn them. And casters have enough pretty toys that I sure don't mind them taking some risk. That said, some of the worse-offending spells for abuse are the out-of-combat ones (simulacrum, planar binding, etc.) that you can just try again to cast the next day. From that perspective, having a chance to lose the spell and/or being dazed 1 round really is not "dangerous" at all.

3. "On a Critical Success, the caster may apply any one metamagic feat they have obtained to the spell without increasing the spell’s level." Looking at records of egregious abuse throughout 3.0 and 3.5 has led me to the conclusion that "free metamagic" perks are like in-laws: the less you see of them, the more you like them. If I were in a game where every spell had a nearly 10% chance (2 dice, 20 on either = 0.098) to be Quickened (or worse, Dazing) for free, I'd go out of my mind.

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My biggest concern about this system is that I'm not seeing what it accomplishes beyond adding a random chance for a spell to fail AND a random chance for it to invoke a wild magic event. It just makes spellcasting less reliable while adding no extra gameplay to it. Often the best systems that use "random failure" have some way of playing around it or influencing decision making. For example, magic in Shadowrun has a random chance to exhaust or harm the spellcaster. What makes that magic system interesting is that the probability is based on how much power you put into the spell. This facilitates gameplay by making the player weigh the risk versus the reward of putting all of their power into a spell.

There's none of that here. You roll a 2d10. If you're lucky, the spell goes off. If not, the spell fails. If the dice gods hate you, then something bad happens or your character just dies. There's no depth there.

On top of it, the system feels overly complicated. A lot of the math and the rolling could probably be condensed down. While it's neat to roll both to determine controlling a spell and determing a spell's power, I feel you could reduce that to two caster level checks. Heck, you could probably reduce it to a single check considering that the control die's math is really simple. Why not make the whole thing a caster level or a concentration check but with a critical failure system based on the natural result? For example, maybe casting a 4th level spell requires a concentration check and if you roll a natural 4 or lower, you cause a wild magic event? Maybe the DCs are based on caster level so you can choose to reduce the probability of failure by lowering the spell's CL?

I also don't recommend the changes to spell resistance. Adding a scaling bonus basically makes it impossible to affect creatures with spell resistance due to the fact that saving throws already scale with HD. SR isn't suppose to make it impossible to affect a creature with magic - it just adds an extra point of failure. It would be better to just add a flat bonus or have the power die determine whether the spell bypasses SR.


First off, let me apologize for the delay. For some reason, I've been unable to access the forums from any computer other than my phone, and I really didn't want to attempt digesting the input and responding on my phone.

Kirth Gersen wrote:
1. It looks like the Power die is essentially doing the same thing as a Concentration check to cast defensively, except it applies all the time. The obvious question, then, is "What happens when I cast defensively?" Do you make both checks (clunky and a drag on play time)? Do you make the Power check at a penalty?

This is actually something I had overlooked. I'd definitely add a penalty, but I need to math out what that would be.

Kirth Gersen wrote:
2. I know there are logical reasons I should dislike adding randomness like wild surge tables, but they're so daggone fun, to me, that I can't bring myself to condemn them. And casters have enough pretty toys that I sure don't mind them taking some risk. That said, some of the worse-offending spells for abuse are the out-of-combat ones (simulacrum, planar binding, etc.) that you can just try again to cast the next day. From that perspective, having a chance to lose the spell and/or being dazed 1 round really is not "dangerous" at all.

That is true. Perhaps increasing the risk of escalation to the more sever tables for higher level spells?

Kirth Gersen wrote:
3. "On a Critical Success, the caster may apply any one metamagic feat they have obtained to the spell without increasing the spell’s level." Looking at records of egregious abuse throughout 3.0 and 3.5 has led me to the conclusion that "free metamagic" perks are like in-laws: the less you see of them, the more you like them. If I were in a game where every spell had a nearly 10% chance (2 dice, 20 on either = 0.098) to be Quickened (or worse, Dazing) for free, I'd go out of my mind.

I want to institute some mechanic for critical success that can be applied to all spells, not just direct damage/healing. Do you think it would be more balanced if the critical success required both d20s to roll natural 20s?

Thanks for the input!


Cyrad wrote:

My biggest concern about this system is that I'm not seeing what it accomplishes beyond adding a random chance for a spell to fail AND a random chance for it to invoke a wild magic event. It just makes spellcasting less reliable while adding no extra gameplay to it. Often the best systems that use "random failure" have some way of playing around it or influencing decision making. For example, magic in Shadowrun has a random chance to exhaust or harm the spellcaster. What makes that magic system interesting is that the probability is based on how much power you put into the spell. This facilitates gameplay by making the player weigh the risk versus the reward of putting all of their power into a spell.

There's none of that here. You roll a 2d10. If you're lucky, the spell goes off. If not, the spell fails. If the dice gods hate you, then something bad happens or your character just dies. There's no depth there.

I totally understand what you mean. Honestly, I did want to include something like that from the beginning, but it got lost somewhere in the mix of calculating DCs and attempting to create the special abilities of the casting classes.

An idea I was toying with was transposing the WFRP system a little bit more whole cloth. What I mean is that casting rolls are made with a pool of d10s. At 1st level (or whichever level a caster gains their first level spells), they are granted 1d10. Whenever they gain the ability to cast a new odd level of spells (3rd, 5th, 7th & 9th), they gain an additional d10. When casting a spell, the caster can choose how many dice they roll at a time, then add the totals to see if they beat the spell's power DC. Doubles, triples, etc. cause wild magic effects, and rolling all 1's results in the critical failure effect. Obviously, I'd need to rework the target numbers and other balance issues, nor have I determined defensive casting works.

I was moving away from this system, as it doesn't feel like a d20 system mechanic, but it does grant some of the risk/reward dynamic you were mentioning from Shadowrun.

Cyrad wrote:
On top of it, the system feels overly complicated. A lot of the math and the rolling could probably be condensed down. While it's neat to roll both to determine controlling a spell and determing a spell's power, I feel you could reduce that to two caster level checks. Heck, you could probably reduce it to a single check considering that the control die's math is really simple. Why not make the whole thing a caster level or a concentration check but with a critical failure system based on the natural result? For example, maybe casting a 4th level spell requires a concentration check and if you roll a natural 4 or lower, you cause a wild magic event? Maybe the DCs are based on caster level so you can choose to reduce the probability of failure by lowering the spell's CL?

I like this suggestion, and will definitely attempt some additional tests with it.

Cyrad wrote:
I also don't recommend the changes to spell resistance. Adding a scaling bonus basically makes it impossible to affect creatures with spell resistance due to the fact that saving throws already scale with HD. SR isn't suppose to make it impossible to affect a creature with magic - it just adds an extra point of failure. It would...

Another good point. I didn't think of the issue with stacking. My main issue with SR is the way it doubles down on defenses for certain spells, particularly evocation. For instance, scorching ray has to deal with touch AC, energy resistance and SR. If you've run into similar concerns, how have you dealt with them?


While we're sorta on the vein of old Warhammer magic systems, you consider going off the classic Dark Heresy system? I personally found that a much more elegant system than ye olde WHFR.

It would take some fiddling to properly transpose it (especially if you want to make up Overbleed) but it's still a wonderful premise of control vs power

(If you haven't played it, the system essentially works by choosing to roll a number of d10s up to your power rating with a static modifier of your casting stat. Meet the target number for a spell to cast it and any time a die is a 9, roll on psy phenomena [roughly equivalent to Tzeentch's Curse] overkilling the target number often gave benefits to the manifestation called Overbleed)


Thanks for the suggestion, I'll look into it, although the base 1 in 10 risk of "wild magic" seems a bit harsh.


It's less harsh than you'd think. Phenomena is more or less analogous to the minor table in WHFB with a good half of the table just being spooky stuff happening that doesn't actually do anything (temperature drops, paintings start crying blood, food spoiling, etc). It's when it upgrades to the second table (75+ on a d100 roll if memory serves) do the effects start getting nasty (being a combination of the major and catastrophic tables depending on where you roll).

Of course you can tweak the system fairly easily like just using the WHFB charts instead of the psychic table or having subsequent 9s past the first add 10 to the bad stuff table (or upgrade to the next table) rather than being an additional roll, etc. Another possibility and similar to how later editions handled it is that rather than 9s, phenomena procced on rolling doubles on your manifestation roll which coincidentally would make casting off a single die perfectly safe.


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I've added the bones of two variant takes on the system: a "Risk & Reward" variant that retains the 2d10 mechanic, and a d10 based system.

Document can be found here

Any input is appreciated!


Bump for additional input!


The difficultly in controlling magic you suggest here can actually be a very good thing, if you are shooting for a campaign which features a lower chance of having spell casters. Does your magic rules also apply to magic items? Scrolls, wands, perhaps even potions? Are the common folks, members of the military, nobles & rulers afraid of magic due to its potential to go wrong?

In my campaign conjuration magics (specifically any spell which summons anything or any form of teleportation) could tear a rift into a demonic plane and allow a demon to escape (based upon the level of spell). Thus having an portal open up in the middle of a city would send everyone and their dog either running away, or coming to investigate.

Randomized magic CAN add a lot of flavor to a campaign setting, as well as discouraging PC's from playing magic heavy characters.

Another consideration: are you concerned about the ability of magic to effect your campaign in ways that you as the DM have not considered, thus leading to these mechanics as a way to restrict magic? One option is to simply restrict magic beyond a certain spell level (my campaign had a spell level restriction of 6th level).

Anyway, just my thoughts.


Lazlo.Arcadia wrote:

The difficultly in controlling magic you suggest here can actually be a very good thing, if you are shooting for a campaign which features a lower chance of having spell casters. Does your magic rules also apply to magic items? Scrolls, wands, perhaps even potions? Are the common folks, members of the military, nobles & rulers afraid of magic due to its potential to go wrong?

In my campaign conjuration magics (specifically any spell which summons anything or any form of teleportation) could tear a rift into a demonic plane and allow a demon to escape (based upon the level of spell). Thus having an portal open up in the middle of a city would send everyone and their dog either running away, or coming to investigate.

Randomized magic CAN add a lot of flavor to a campaign setting, as well as discouraging PC's from playing magic heavy characters.

Another consideration: are you concerned about the ability of magic to effect your campaign in ways that you as the DM have not considered, thus leading to these mechanics as a way to restrict magic? One option is to simply restrict magic beyond a certain spell level (my campaign had a spell level restriction of 6th level).

Anyway, just my thoughts.

Thanks for the input!

So, yes, any campaign setting in which this system would be used would most likely be one in which magic is feared by the common folk and interchangeably used and feared by the nobility.

I'm aware of the effects that high level magic can have on a campaign setting, and concern over those effects is not the driving force behind this project. Mainly, I feel that magic is too guaranteed, too safe in PF/D&D. The idea of dangerous magic that is unpredictable without the most rigorous care and focus is exciting to me, and I want to make sure that the system is sustainable before offering it to my table.


A lot of things can go wrong, maybe spell specific.

Maybe teleport displaces an equal mass. When they teleport somewhere, a section of wall or some enemies are teleported back.

How about every healing spell harms some random NPC somewhere.

A fireball in one place causes flash freezing in another.

The lightning bolt spell causes all the clouds in the area to become thunderstorms.

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