Homebrewing a second magic system?

[MonkeySage]

In a recent session, I included for storytelling purposes a binding sigil. When drawn properly on a door, this sigil is able to nearly completely block the movement of a certain type of being. It can transform the flimsiest wood into an impenetrable barrier. This mostly served the purpose of communicating to the players "The thing behind this door is very dangerous", and according to my players it did this job well.

I'd like to expand on this though, now that I've established that this sort of magic works. No spell need be cast for these sigils to work, but they're complicated and require high mysticism to use. They're intended to be very specific and limited in their use. That binding sigil doesn't block anything but outsiders.

This is meant to be general, no specific game in mind. Just guidelines. What should I keep in mind when working on this?

[AtlasSniperman]

May I shamelessly plug this as inspiration?

http://www.giantitp.com/forums/showt...Magic-in-zones

[khadgar567]

May I shamelessly plug this as inspiration?

http://www.giantitp.com/forums/showt...Magic-in-zones

I think this is not he wants.

[JoshuaZ]

In a recent session, I included for storytelling purposes a binding sigil. When drawn properly on a door, this sigil is able to nearly completely block the movement of a certain type of being. It can transform the flimsiest wood into an impenetrable barrier. This mostly served the purpose of communicating to the players "The thing behind this door is very dangerous", and according to my players it did this job well.

I'd like to expand on this though, now that I've established that this sort of magic works. No spell need be cast for these sigils to work, but they're complicated and require high mysticism to use. They're intended to be very specific and limited in their use. That binding sigil doesn't block anything but outsiders.

This is meant to be general, no specific game in mind. Just guidelines. What should I keep in mind when working on this?

My advice is going to be mainly in a 3.0/3.5/PF context, but the basic idea it will apply to some others. Having a system of sigils where one simply needs to like this will mean that you are increasing the power of classes which are "high mysticism", e.g. wizards, sorcerers and clerics. This has a risk that if it is grafted on for free (simply knowing a sigil allows one to use it) that you will be providing a power boost specifically to the already most powerful classes. Therefore, it may make sense that they have to give up something; maybe learning a sigil requires giving up a skill point, or maybe using sigils in general requires a feat and then you can use any of them that you know.

With that out of the way,

While AtlasSniperman's system isn't quite what you want, it sounds like some basic aspects may be useful, sigils of varying complexity with higher skill checks (maybe knowledge(arcana)) to get right. So doing something similar to what he's done isn't a bad idea.

[Hish]

The other option is making the magic available to noncasters as well. In that case, casters only have the advantage if you use skill checks like spellcraft, which they will probably have ranks in, or if a given character doesn't want to use any magic for flavor reasons.

Skill checks are good. It's dangerous to make the effects scale with the check though, because it is easy to pump a skill incredibly high. Use flat check to create a given sigil.
Another idea is requiring a (cheap) magic item to create sigils in the first place. A specially enchanted set of scribe's tools, for instance. I'm not sure it's a good idea, but it might help get the creative juices flowing.

[JoshuaZ]

Skill checks are good. It's dangerous to make the effects scale with the check though, because it is easy to pump a skill incredibly high.

Good point about the danger. There are a few ways I have seen which work with scaling skill checks to prevent issues. First, maximum amounts it can scale so there is some range but it cannot scale beyond that range. Second, have a scaling which is sublinear with the skill check. For example something might scale giving a bonus at DC at perfect squares. Third, having scaling only on things where really high values do not matter much-this may be the hardest option. Fourth, have one not be able to scale beyond some numeric value. For example, if using Spellcraft maybe the check cannot effectively scale beyond twice your ranks in Spelllcraft or maybe the check is Spellcraft but the max scaling is a function of knowledge arcana.

[aimlessPolymath]

Without reference to a particular system or implementation, the defining characteristics you've described/my thoughts on them:

-Available without needing access to the greater magic system. It is either gained through unique knowledge (i.e. being passed down in an organization, learned from others), or through a character advancement option other than that used to gain magic normally (i.e through skill checks or feats rather than class level). In the first case, access to these sigils is analogous to a magic item, of sorts- it's something that anyone might pick up, and gives them additional powers beyond another character. An example of the second version might be a feat that lets you learn the Three Sigils of Sealing (The Sigil of Immobility, the Sigil of Opposition, and the Sigil of Containment), to make up some names.

-Specific. Each sigil is one narrow effect, meaning that players either
a) Are able to learn new sigils out of combat in preparation for expected encounters (mode 1 access). The skill checks people seem to be suggesting might fall into this category.
b) only interact with sigils as preprepared plot devices
c) Are able to learn large numbers of sigils, letting them deal with a variety of encounters (such as with my example feat- you will rarely need to bar a region against outsiders, make an object immovable, or create a region that no spell effects or magic auras can exit, but one of the three will come up occasionally). The skill checks people seem to be suggesting might fall into this category.
d) Have them as a minor part of their character sheet, analogous to traits in Pathfinder- only a few will be learned, and they will rarely come up unless the plot is contrived to be so.

[PairO'Dice Lost]

If you want to keep things both specific and limited, the most important thing is to figure out what the overarching function of these sigils is and the reason for their existence. You already have one sigil that blocks entrance by one kind of being--let's call it the Sigil of Exclusion for the sake of argument--but why is the sigil able to do that, exactly?

• Is it because sigils have a mystical resonance with that kind of being, so you could also have a Sigil of Proximity that glows when creatures of that sort are nearby, but you couldn't have a Sigil of Hatred that blocked a different kind of being?
• Is it because sigils have a mystical association with boundaries and barriers, so you could also have a Sigil of Forbiddance that can create an invisible barrier around the place where it's scribed, magic circle-style, but you couldn't have a Sigil of Elevation that creates a floating invisible surface to stand on?
• Is it because sigils can mystically enhance the metaphysical properties of objects (like a door's ability to determine who can enter), so you could also have a Sigil of Illumination that makes a candle much brighter, but you couldn't have a Sigil of Stamina that increases a creature's strength?

If the sigils' capabilities are too open-ended, you risk making a system that's basically "normal magic that can do anything, but with fancy sigils as a special effect." Strictly limiting what kinds of things the sigils can do to start not only makes it much more thematic in contrast to normal magic, but it also lets you make the sigils pretty darn strong (like the example sigil, which is basically "Creatures of X type can't get through, period, no exceptions") without risking them being a balance issue.

Doing this also helps you determine how characters should be able to access them. To use 3e terms, if sigils are creature-type-specific, then a Knowledge check relevant to that monster type might be how you use one, and characters might be able to learn a number proportional to their knowledge ranks. If sigils are about metaphysical properties of objects, then some sort of special Wis-based check to identify appropriate properties to enhance would be more appropriate than a skill check, and perhaps you can learn any number of sigils but have to do things like meditate in a forest to learn wood sigils, meditate under the noonday sun to learn light sigils, etc. so it's limited mostly by time and obscurity. And so forth.