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View Full Version : [BRP] Help me design a new magic system



fmitchell
01-20-2009, 02:33 AM
(Note: I accidentally closed the last window I was typing in, so I'll be brief this time.)

I'm designing a ritual magic system for BRP. Instead of a straight percentile roll for each ritual, I've decided that the factors influencing the success of a ritual are the following:


The caster's POW (positive, 10-21, usually)

The caster's Allegiance to a relevant god or power (positive, % score)

The power level of a ritual (negative, undecided units)

Ritual-specific bonuses for time, place, material components, skill checks, or knowledge (positive, undecided units)

My first idea was a simple percentile roll, based on the following formula:

(POW - Power Level) x 5% + allegiance bonus + ritual-specific bonuses

However, I wonder if that's too much calculation at the table. I don't want to slow down the action, even if rituals by their nature happen outside of combat time. Also, I wonder if POW should be such a heavy influence, especially for high-powered rituals like weather control or mass mind-altering effects.

Maybe if I rank Power Level to 1 - 5, 1 being the most difficult, the formula could become:

POW x (Power Level)% + allegiance bonus + ritual-specific bonuses

But that's at least as much calculation ... more, given that I have to pre-compute POW x 1% to POW x 5% for the caster. (I just can't do arithmetic in my head.)

Any other ideas? I can provide more information upon request.

Skunkape
01-20-2009, 06:51 AM
I'll have to give it some thought, can't guarantee I'll come up with anything, but I'll mull it over some.

A quick few cautions, which I see you've already thought about but I want to reinforce, be very careful with on the fly calculations at the table, you're right in that they will slow down the game. When I ran a couple of sessions using BRP, we didn't have crit and special values pre-calculated and my players didn't like having to take a few moments to work out those values, so I'd say the same will likely happen with a full blown skill calculation like what your considering.

I've always wanted to do an on the fly spell system, where the player decides effective range, power, area of effect, etc of a spell, but I've never been able to come up with a good system that would be quick and easy to use.

But I'll give it some more thought and let you know if I come up with something meaningful.

fmitchell
01-20-2009, 07:44 AM
What really messes it up for me is using Allegiance, which is a percentile score. Otherwise I'd steal from two of the system's inspirations, the "Occultism" system from Fudge's A Magical Medley and Buffy's Sorcery system: roll POW + bonuses + (some die) against a target number of the ritual.

I've considered a bifurcated system, where I roll a percentile against Allegiance (which grants another bonus), and then roll-over based on POW and "props" (the aforementioned bonuses for time, place, and materials). But rolling d% and then 1d20/3d6/2d10 is kind of time consuming in itself.

I'm also thinking of classifying rituals, each of which has a different emphasis on raw POW, Allegiance, and ritual components. E.g. direct summoning rituals rely on raw POW, but invocations of a god's power rely largely on Allegiance.

Alas, I also need to make room for group casting, whereby a leader and acolytes can do greater magics than one magician alone.

For reference, here's how I describe the system in a Players' Pack:



Ritual Magic, the most common type in the Orc Lands, involves contact with the Spirit World through lengthy rituals, anywhere between ten minutes and several days. Dealing with spirits is a slow and tricky business, and a practitioner must build up a relationship with members of the Spirit World in order to work greater magic.

Among the People, magic is mainly the province of shamans. Shaman characters begin with basic magic rituals; others must discover them as play continues. Shamans should see the GM for a starting list of rituals.

To perform Ritual Magic a practitioner must have a ritual written or memorized. The simplest rituals allow mortals to speak to local spirits, ask a blessing, send a curse, or travel through the Spirit Realm; more powerful ones compel or banish spirits, call down nature's wrath upon enemies, create charms to protect or harm mortals, or meddle with
mortal minds.

The Knowledge (Spirit Lore) skill aids in improvising magical new rituals from known ones, evaluating found rituals, and understanding the ways of spirits. The Research skill can help discover forgotten spells in musty tomes.

The magician and any assistants creates a sacred circle, and conduct the ritual over minutes, hours, or sometimes days. The GM rolls secretly to determine the effect of the ritual, and announces the result ... which may not always correspond to what a magician intended.

Factors influencing the success of a ritual include, but are not limited to:

the ritual leader's POW
the number of assisting characters and their POW
special knowledge or significant items woven into the ritual, e.g. the name of a particular spirit, or an offering that spirit likes
results of skill or characteristic checks required by the ritual, if any, e.g. Perform, Craft, or Stamina
the location of the ritual, e.g. the grave of a ghost a character wishes to speak to, or a sacred grove
participants' Allegiance to relevant spirit powers, if any.

Allegiance is a percentile value, built up during play, resulting from "favors" done on behalf of one or more major players in the Spirit World. The GM keeps the Allegiance value(s) of a character secret, although players can guess how indebted the spirits are based on their own actions. In the Spirit World, who you are matters as much or more as what you know.


The third, fourth, and fifth items are lumped together as "bonuses" in my formulation above.

Webhead
01-20-2009, 10:53 AM
What really messes it up for me is using Allegiance, which is a percentile score. Otherwise I'd steal from two of the system's inspirations, the "Occultism" system from Fudge's A Magical Medley and Buffy's Sorcery system: roll POW + bonuses + (some die) against a target number of the ritual...

If you think it may be useful for inspiration, I could post some of my notes about tweaking the Buffy/Angel Sorcery system to emulate the magic seen in The Dresden Files novels.

MortonStromgal
01-20-2009, 10:54 AM
If you want to speed it up you could have it pre-calculated to a point on the character sheet.

fmitchell
01-20-2009, 11:19 AM
If you want to speed it up you could have it pre-calculated to a point on the character sheet.

Yeah, that's what I was planning on doing. In fact, since I wanted to keep some details of a character's "magical presence" secret, I was planning on having a "spirit world sheet" of my own with the character's POW, Allegiance to the major supernatural powers (four or five), and any other pregenerated data.

However, bonuses for optional props per ritual might be tricky ... or not. Also, I'd rather come up with a "roll over" mechanic so I can compare positive factors to a target number instead of figuring (POW - Level) for every ritual known.

boulet
01-20-2009, 09:34 PM
And what about making the spell casting resolution be composed of two phases :
1 - the PC perform the ritual (whatever the color of the settings implies) using a relevant skill check (something along the lines of shamanism, singing, theology...) Some modifiers are applied to reflect the degree of atonement of the shaman/priest, the adequacy of location, quality of sacrifice, holiness of the day etc...
2 - If the ritual was successful then and only then can the POW derived check happen, meaning the prerequisite to invoke any power is a proper ritual.

A little detail : as a player I would have troubles to conciliate shamans and old books of spells. When I hear shaman, I expect oral traditions, master-disciple relationship and stuff like that. It may be completely coherent in your setting, so just my two cents.

McCummhail
01-21-2009, 10:38 AM
If you think it may be useful for inspiration, I could post some of my notes about tweaking the Buffy/Angel Sorcery system to emulate the magic seen in The Dresden Files novels.

Unrelated to the current discussion, I am interested in seeing your Dresden Files magic system. I was looking to run a modern fantasy and this could be a great fit!

Skunkape
01-21-2009, 11:07 AM
I really can't think of anything to add that would be helpful other than I think I'd keep the role for the ritual to function to be just one, and have it function against a skill check. As far as including power into the mix for rolling against the power to function, if I included a roll for that, I would make it against the resistant table and more than likely having it a function of the effectiveness against the target.

I think that creating a base skill percent that would be recorded on the player sheet and possibly modifying that value by circumstance modifiers sounds like the best plan. Less math that way.

Webhead
01-21-2009, 11:33 AM
Unrelated to the current discussion, I am interested in seeing your Dresden Files magic system. I was looking to run a modern fantasy and this could be a great fit!

Will do. When I get home and have some time, I will create a new thread to post my notes into. My current Unisystem Dresden Files material includes rules for magic, a few new Advantages/Disadvantages and some creature templates for the more common types of beasties in the Dresden-verse.

fmitchell
01-21-2009, 12:27 PM
Thanks for the advice, but I don't know how much of it I'm going to use. First off, let me state some design decisions I made early on:

My prime inspiration for the system is "Occultism" from the Fudge supplement A Magical Medley, where making magic work depends on an inherent "Sixth Sense", and the "shamanism" skill only allows one to design and validate rituals. That system also provided the notion of "props", a way to increase the initially steep odds of making a ritual work.

Other influences are Sorcery from the Buffy RPG (and Ghosts of Albion), and Spirit Magic from GURPS Voodoo, Spirits, and Thaumaturgy.

Because of "Occultism", I decided against a Perform (Ritual Magic) skill, using instead the POW of the ritualist. Within the game, the rituals themselves aren't too hard to perform, usually. The question is whether the spirits show enough interest in the performers to show up.

I'd like to keep dice-rolling to a minimum, under the adage "roll when something interesting happens either way".

Finally, I wanted to inject some mystery into magic, so I'd like to keep the values of some variables, like Allegiance, secret. That might go for the importance of some "props", the power level of a ritual, and


A little detail : as a player I would have troubles to conciliate shamans and old books of spells. When I hear shaman, I expect oral traditions, master-disciple relationship and stuff like that.

The PC's culture is both animist and literate, so it made sense to me that shamans might write down rituals.

Thinking back to the original "Occultism" system, maybe this is how it should work: Each ritual has a Base Chance (often horribly low), a list of required props, and a list of optional props that increase the base chance. A POW modifier and a relevant Alliance also adds to the base chance. The GM adds all these factors up (or pre-adds them for extra speed), and makes a simple percentile roll. When the shaman is dealing with an unwilling spirit, maybe a POW vs. POW roll would also be involved.

I guess what I really should do is enumerate a set of rituals from basic techniques to the esoteric and dramatic. With the above as a basic framework, I can use a spreadsheet to tweak the details.