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Due to their ubiquity, and the multiple types of information conveyed through them, I personally don’t think there’s a “one true way” technique for handling passive perception tests. Partly because everything is a trade-off. Partly because the “one true way” is what allows the players to reliably reverse engineer from the information they have to the problematic metagame knowledge we’re trying to avoid. What I have instead is a cluster of techniques that I’ve found work well when you use them collectively – but not necessarily simultaneously – over the long-term. The techniques sort of weave together to form a tapestry that’s greater than the sum of its parts.

EXTRANEOUS TESTS: First, obfuscate the meaningful perception tests by calling for perception tests regardless of whether or not there’s anything interesting to be spotted.

Although these tests are, in some sense, “meaningless,” that doesn’t mean that they can’t be used for effect. The most obvious such effect, of course, is paranoia: “But I rolled a 28! What do you mean I don’t see anything?!” So call for these checks when things get a little spooky and it feels as if the PCs should be on edge. You’re performing a kind of judo here, turning the metagame knowledge on its head and using it to good effect.

Eventually, of course, players will figure out that you’re frequently “crying wolf” with these checks. At that point you can go for second order effects, using the checks to create false complacency: “I rolled a 28 and got nothing? Eh. GM must have been bluffing us.” And then the ninjas stab them.

If you pull that off a couple of times, the paranoia will start rolling back in. As a basic technique, you can get pretty far just riding this oscillation back and forth.

What Not to Do: I’ve seen some GMs who attempt to simply integrate passive perception tests into a regular routine. For example, they might have the group roll a perception test every time they enter a new room in the dungeon. My experience is that, compared to integrating extraneous checks for effect, this doesn’t work very well: Perception tests do chew up time and they do pull people out of the game world to some extent so that they can fidget with their dice. Furthermore, when they’re made routine, they’re often inserted habitually at the point where the PCs are encountering something new… which is the exact point where you want to maximize player engagement, not disengage for a mechanical interaction. (This is the same reason that I roll initiative checks at the end of combat.) If you want to pursue a “perception as regular routine” approach, I recommend embracing a very liberal let it ride technique to minimize the frequency of these checks. (Although, unfortunately, this will begin to reintroduce metagame knowledge issues, with the group getting an uncanny sense of how aware they’re going to be for a particular delve or run.)

REFOCUSING THE TABLE: As I mentioned in The Art of Rulings, extraneous perception tests are also the single most effective way to refocus the table’s attention on the game world when metagame distractions and chitchat have derailed the players. (You’d think that just saying, “Okay, let’s focus,” would be equally effective, but I’ve found that it isn’t. If you ask people to focus, they start up a sort of general “focusing process” that often includes apologizing, further dithering, and otherwise not focusing. Ask them to do something specific and concrete, on the other hand, and they become immediately focused.)

Of course, sometimes you can refocus the table by calling for a perception test to notice the incoming bad guys heading their way. So sometimes the meaningless “let’s refocus, guys!” test will, in fact, turn out to be quite meaningful.

INNOCUOUS INTEREST: Which brings us to the next thread of the tapestry, in which the “meaningless” extraneous perception tests are actually being triggered by more casual elements of the game world: There are claw marks in the ceiling, or the base of the idol has been rubbed to a bright sheen, or you think that you can detect the smell of a cooking fire from somewhere down the left hand corridor, or you take note of a particularly interesting historical detail in the painting on the wall.

Now there is no “bluff” at all. It’s just that when the PCs miss a perception test, the players have no way of knowing whether it was for an ambush or for noticing the local style of pottery.

A WORLD OF (NEAR) INFINITE INTEREST: Of course, now that we’ve convinced the players that there is no bluff, that’s exactly what we’ll do. A good check will always result in them noticing something, even if it wasn’t the primary thing that triggered the test. You rolled a 45 but you needed a 47 to notice the assassin hiding behind the arras? I’m still going to tell you about the claw marks, the idol’s sheen, the smell of cooking, and/or the historical detail in the painting on the wall.

So now, even if they appear to have succeeded on the test, the players can’t be certain that it wasn’t actually a failure in some broader sense.

Improvising these details is also just a really great way to develop the depth of the game world. But this is also a great opportunity to expand the dynamic scope of the environment: Sound and scent can be perceived without a direct line of sight, allowing you to hint at things nearby. Active elements of the area can also have affected the immediate surroundings of the NPCs (i.e., who or what has passed through here?). If you’re in a dungeon, check your key for nearby areas, look at your adversary roster, or roll on you random encounter table for inspiration.

OVERLAP OF PASSIVE & ACTIVE TESTS: Another technique is to overlap the demesne of passive and active perception tests. In other words, if your passive perception test is good enough, you’ll notice stuff that would normally require you to actively search the room.

The distinction here can be very clear in systems which use different skills for active vs. passive perception. For example, in 3^rd Edition D&D I allow Spot checks to effectively function as Search checks with a -20 penalty. (So if you roll 40 on your Spot check, you’ll notice traps, secret doors, and other hidden stuff that would normally require a DC 20 Search check.)

I find this is a great way to reward players for their areas of specialization, while emphasizing how awesome their higher level characters really are. It’s also a good technique to use if you’ve called for an extraneous passive perception test and someone gets a really amazing result: Check your notes and see if there’s an active search check (or even just something that you’d assumed would require specific observation) to notice.

(If you’re using the system described in The Art of the Key, I’m basically saying “check your bullet points.” If you’re struggling to figure out how certain items could be discovered through passive perception, check Matryoshka Search Techniques.)

SPLIT GROUPS: As a minor technique, when the group is split up, you can also ask for a passive perception test from everyone. Now they don’t even know which group (if either) actually had the triggering condition! And sometimes it’ll be both! (You can use thematic crossover techniques to unify the disparate action. You can see a humorous example of this in my Ptolus campaign journal.)

THE ULTIMATE EFFECT: So sometimes you make a perception test, and you don’t notice anything because it was a “fake” check, but sometimes it was because you failed it. And sometimes you notice something, but it was actually still a failure. And sometimes you notice the same sort of thing, but it will be because you succeeded on the test.

What the GM has done is obfuscate the true meaning of the test, and then obfuscated the obfuscation with an interwoven labyrinth of techniques. (And, importantly, most of these techniques are adding additional layers of value above and beyond simply obfuscating the purpose of your perception tests.) The result won’t completely obliterate every trace of metagame knowledge contained in the call for a perception test, but it doesn’t have to: It just has to introduce enough noise that the players’ won’t be able to reliably pick out the signal.

One particularly memorable group, for example, thought that they’d identified a “fake test” that I was using “just for effect”. Nope. They’d actually just missed their NPC “ally” pick-pocketing the magical artifact they were supposed to be guarding. When they realized what had happened, that was their breaking point and they gave up on that kind of metagame thinking.

The truth is most players aren’t actually interested in the metagame knowledge. But if the information is just lying there in plain sight, they can’t help noticing it… and then obsessing over it. It becomes this whole thing. In my experience, if you hide the information just a little bit and make it unreliable even when they do look at it, you’ll quickly break the instinct. (In a sense, you’re just trying to crank the DC for their passive perception test high enough that it would require an active perception test to notice the metagame knowledge.)

WHY BOTHER?

You may have noticed that we’ve been ignoring the elephant in the room: Why bother with all this? If the GM simply rolls all the checks, that’s a perfect solution for the metagame knowledge problem. So why are we not just doing that?

First, because, as I noted before, it doesn’t always work. Any limited resource that would impact the passive perception test (whether a meta-mechanic or otherwise) or player-faced mechanics in general prevents the “GM rolls” solution from being used.

Second, because I’m faux lazy. As a general rule, I try to push as much bookkeeping off my plate as the GM and onto the players as possible, because everything I keep on my plate is, in fact, a trade-off. I’ve found that there’s always room for more stuff that I could be tracking behind the screen to enhance the game. This also, as previously mentioned, tends to increase the accuracy of the result.

Third, as an experienced GM you learn how to take advantage of the momentary pause as people roll their dice: You multitask. You call for a check and you do this other thing while people get their results and then you grab the results. Passive perception tests, unsurprisingly, tend to occur just as you’re setting up for something new, and using that momentary pause to get your notes lined up for whatever that is turns out to be incredibly useful in keeping the game flowing forward. At a certain point, not only losing that crucial moment of prep but adding to it the time necessary to resolve all those passive perception tests yourself just starts feeling kludgy as hell.

Fourth, the refocusing thing works really well. You can take that technique away from me when you pry it from my cold, dead hands.

Fifth, I’ve found that this approach tends to have positive effects in general. Players who learn to stop trying to glean metagame knowledge from perception-type resolutions often also stop engaging in that behavior in other situations, too, either because they’ve learned that it’s not worth the effort or (more often) because they never really wanted to be burdened with the metagame knowledge in the first place. You win the battle in one place and you break the wider, often subconscious, habit across the board.

Go to Part 3: Divided Perception

With the possible exception of combat-related tests, I suspect that perception-type tests are the most common skill tests in RPGs: What do the characters see and when do they see it?

Despite their ubiquity – or perhaps because of it – perception-type tests are surprisingly challenging for many GMs, and the art of their use can be surprisingly contentious, with those choosing to resolve them in one fashion often feeling that those who resolve them using different techniques are heretics who are ruining their campaigns. (No joke.)

Let’s take a moment to further refine our field of study. Perception-type tests, broadly speaking, can be broken down into two categories: Active perception tests (determining what the character notices when they are consciously making an effort to observe) and passive perception tests (determining what a character notices reactively and/or while engaged in other activities).

Of the two, active perception tests tend to pose little challenge or oddity: The player states their intention and method, and then the action is resolved. There may be some fiddling about with hidden vs. open stakes and difficulty numbers, but these tests are fundamentally resolved like most other tasks.

When it comes to passive perception tests, however, things get more complicated, primarily because such checks inherently create significant metagame knowledge (i.e., knowledge that the player possesses which their character does not): The test, after all, is being made to determine whether or not the character is aware of something. But the mere fact that the test is being made in the first place reveals to the player that there is something the character is (at least potentially) unaware of.

This is problematic because:

• Even if the check is successful, the argument can be made that the significant bifurcation of the player’s experience from the character’s experience is non-optimal.
• It deadens the sense of surprise. (A jump scare is less effective if you know it’s coming.)
• It lets players to abuse their metagame knowledge, allowing them to take actions based on the fact that the test was made.
• Even if the player attempts to avoid such abuse, the mere presence of the knowledge can complicate the decision-making process, filling it with an extra burden of doubt and self-analysis. (For example, maybe you would have been extra cautious about that door up ahead even if you weren’t aware that the GM called for a perception test as soon as you saw it… but are you sure? And even if you’re sure, what will your fellow players think of your choices?)

In order to avoid this cluster of problems created by the metagame knowledge of the passive perception test’s existence, GMs have adopted a variety of special procedures for such tests. Let’s take a moment to briefly discuss the major approaches.

THE PLAYER ROLLS

The first approach, of course, is to just resolve passive perception tests by having the player roll them.

PROS: This is usually the way that other skill tests are resolved, so you’re simply being consistent with your methodology.

CONS: The metagame knowledge we just discussed.

THE GM ROLLS

Okay, simple solution: The GM rolls the test in secret.

PROS: The player doesn’t know the test is being made, so there is no metagame knowledge being imparted.

CONS: The GM has to track the pertinent skill ratings for the PCs. This can be difficult to do accurately, particularly if the system features a lot of different perception-type skills or has lots of buffs, equipment, and/or transient character abilities that cause the perception-type skill bonuses to shift around. In many systems it can actually be impossible to do this, as the players will have optional resources or limited use abilities that could affect the outcome of the check.

And even if the GM does execute the checks without error, players tend to have a greater confidence in checks they rolled themselves. “Whaddya mean we got ambushed? Don’t I get a Spot check? Did you remember that I get a +3 versus spotting cyborgs?”

There is also an inherent time cost (one guy making five checks generally takes longer than five people each making a single test) and a potential pacing problem (players actively resolving something are engaged; players waiting for the GM to finish rolling dice behind their screen are not engaged).

VS. STATIC VALUE

Instead of rolling passive perception tests, the PCs’ passive perception is boiled down to a static score which is compared, without a randomizer, to the difficulty of the test.

PROS: This eliminates some of the problems with the GM rolling. Instead of a time cost, this method can actually result in a time savings, which also means that the pacing problems generally don’t crop up.

CONS: Many of the problems, however, remain (such as keeping track of the PCs’ skill ratings).

More importantly, in practice this method effectively turns passive perception tests into pure GM fiat: The GM will obviously quickly learn what the highest passive perception score is in their group, and when they set the target number for a passive perception test they are ultimately just deciding whether it’s higher or lower than the party’s score. There’s nothing inherently wrong with the spectrum of GM fiat, per se, but what you end up with here is this sort of fake mechanic and a bunch of extra bookkeeping which seems to have no real purpose except to camouflage the fiat. If this is the approach you want to take, it seems to me that you’d be better off skipping all the hassle and just embracing the fiat directly.

UNCERTAIN TASKS

As discussed in The Art of Rulings, you could also adopt the uncertain task method described in Traveller 2300. In this method, both the GM and player resolve the test separately, and the combination of those outcomes results in either no truth, some truth, or total truth.

PROS: The method obscures some of the metagame knowledge imparted when the player makes the roll (i.e., they can’t intuit reliably based off their knowledge of what their die roll was). The GM also doesn’t need to track the PCs’ perception scores, because they can just ask for that information as the check happens.

CONS: This resolution method is more time consuming, particularly when you’re dealing with a scenario where everyone in the group is making the passive perception test. Muddling out five different test result comparisons can be laborsome by itself, but the spectrum of potential results can also create a great deal of confusion when different characters getting different results simultaneously. (Maybe you could have everyone roll and then only resolve the uncertain task comparison check with the character who rolled best to determine what the group actually observes?)

Go to Part 2: The Perception Tapestry

Go to Part 1

True rituals are very complicated spells that are the stuff of legend. They are far beyond the power of any single spellcaster and can only be cast in ritual form. They cannot by further augmented by any feats or other abilities. True rituals combine all aspects of magic and have no schools of magic associated with them.

True rituals are cast as normal spells with the exceptions detailed below.

TRUE RITUAL COMPONENTS

All true rituals have verbal, somatic, material, and experience cost components. Each member of the ritual must pay the experience cost. If the ritual is using proxy ritual members to cast the spell (see below), the experience cost of the replace caster(s) is divided equally among the normal casters who are participating in the true ritual. If the experience cost lowers one of the caster’s levels, the lost level must come from the caster’s primary spellcaster class.

CASTERS REQUIRED

Each true ritual has a minimum number of required casters. Each caster must have the spell prepared in the usual fashion at the time of casting. True rituals are prepared in lieu of one of the caster’s spells of equivalent level.

With multiple casters, the power of the ritual is increased. Use the level of the highest caster in the group and add the number of other casters (not proxies) participating in the true ritual to determine the effective caster level. The ritual’s effects are based upon this effective caster level.

PROXIES

Some true rituals allow a proxy in place of one or more of the required casters. The proxy section of a true ritual details who can replace a required caster during the ritual. Proxies cannot replace every caster: There must be at least one spellcaster to lead the ritual.

SAVING THROW

True rituals have more power behind them, which in turn makes them more difficult to resist. Any saving throw against a true ritual has a DC of 15 + the level of the spell + the relevant ability modifier of the highest-level caster participating in the ritual.

COUNTERING RITUAL MAGIC

Dispelling or countering augmented and combined ritual castings of a spell is similar to countering a normal casting of the spell. Of course, the longer casting time offers a larger window of opportunity to disrupt the spell. Throughout the casting, observers get a Spellcraft check (DC 18 + the spell’s level). The DC is slightly higher due to the changes in the prolonged casting, but the longer casting time allows for a retry of the check each round. Using dispel magic to counter an augmented or combined ritual casting is much easier due to the delicate and extended manipulation of the magical energies involved. The dispel check goes against a DC of 6 + the spell’s caster level if the dispel check is made during the casting of the ritual spell.

As with countering metamagic feats, any additional effects or added levels are not taken into account when counterspelling a ritual casting. A regular cone of cold spell counters a ritually enhanced cone of cold.

True rituals cannot be countered with knowledge of the true ritual in question: The preparations are too long and complicated to enact even throughout the hours of casting time required. True rituals can easily be disrupted, however, through combat, distraction, or other means. Unlike augmented or combined ritual castings, any dispel magic checks to counterspell a true ritual go against a DC of 15 + the caster level of the true ritual’s highest-level caster.

RESEARCHING ORIGINAL TRUE RITUALS

Any spellcaster who can cast a true ritual can attempt to create a new, original true ritual. Creating a true ritual, however, is much more demanding than creating a normal spell.

Like the research of a regular spell, the creation of a true ritual requires access to a well-stocked library for a wizard and meditation, prayer, and sacrifices in a major temple or blessed location for clerics and druids. A wizard’s library must be comprised of books, treatises, and manuscripts totaling at least 50,000 gp in value. Magical items and spellbooks do not count toward this total for the personal library’s value.

The research must be conducted by at least three spellcasters of the same type  (arcane or divine) who collaborate on the ritual’s research. During the research, each of the spellcasters must pay 1,000 gp per week with a minimum of one week per effective level of the true ritual. This money goes into the same fees, experimentation, and components that regular spell research consumes. At the end of the research period, each of the researchers makes a Spellcraft check against a DC of 20 + the spell level. If all the researchers succeed, the new true ritual has been successfully created (assuming the spell is viable). If any of the researchers fail, however, they must all go through the research process again if they wish to keep attempting to learn the true ritual.

The criteria for a viable true ritual are entirely dependent upon the requirements of the DM. Use the guidelines for new spell creations found in the core rulebooks. Compare any new true ritual concept with those presented in this chapter.

The following elements are required for all true rituals:

• A minimum of three casters is required to perform a true ritual. More may be required depending on the ritual.
• The ritual must have an experience point cost to cast. Higher experience point costs can balance the power level of some true rituals.
• The number of casters required to cast a true ritual is also the number of casters that are required to research the ritual. Requiring a higher number of creators can also serve to balance the ritual’s power level, though not as much as an experience point cost (and not if the PCs acquire the ritual through means other than research).

This material is covered by the Open Gaming License.