Colin R. asks: “What tricks or devices do you have for generating memorable NPCs? Especially for creating them on the fly when players go in unexpected directions.”

This will not attempt to be an exhaustive discussion of how to create memorable characters. You could write whole books on the subject, and people have. But perhaps a grab bag of techniques I’ve found useful as a GM will prove useful to you, too.

1. Give them a distinct mannerism. I talk about this in the Universal NPC Roleplaying Template, which is itself a good, quick structure that you can pour characters into. A simple, physical action that you can perform at the table — crossing your arms and stroking your chin, scratching your knee, tapping the side of your nose, winking, speaking with a particular accent, scratching the top of your head, a notably colorful preference for a particular swear word — will make it much easier for you to slip into and out of a given character, and make that character more memorable and distinct for the players.

2. Give the NPC a strong agenda. Make them want something. Better yet? A pair of agendas. If they’re agendas that partly conflict with each other, even better.

It actually works best if this agenda is not aimed directly at the PCs. Something that simply overlaps the PCs’ areas of interest is usually more effective. If the PCs’ actions/knowledge/connections/whatever could help (or hinder) the NPC, I’ve found it’s often more effective for the NPC to discover that during their interaction with the PCs. (Or for the PCs to discover it and then decide what to do with that knowledge themselves.)

This is not a universal rule, obviously: There’s nothing wrong with a patron showing up and wanting the PCs to do something for them.

But the less the players think “X exists because the GM wants us to do Y,” the more they will think of X as an actual person.

3. Throw out lots and lots of NPCs and then pay attention to which ones “click” with the players. Focus on those and be OK with letting NPCs that aren’t clicking move on with their lives. I talk about this a bit in Party Planning.

4. Neel Krishnaswami’s Law of the Conservation of NPCs is also useful to remember here:

In our last Nine Worlds session, I introduced Perseus, a captain of the Lunar space fleet, who was married to Nick’s PC’s wife. In the session before that, the players had been boarded by a Lunar ship which had confiscated our engineer’s robot as technological contraband. That ship had a captain, who went unnamed. So when I first mentioned Perseus, the players’ first response was “Hey, is he the same guy?” and my answer was, “Of course — the law of conservation of NPCs demands it!” The players chuckled, and we went on playing.

The principle of conservation of NPCs actually is one of my GMing strategies. Whenever I introduce a new conflict into the game, I try to see if existing NPCs can be integrated into this role before I consider introducing a new NPC. I find two big benefits from doing this.

The first is simply that the size of the cast stays under control — I’ve run plenty of games where NPCs multiplied without limit, and that meant that months of real time could pass before we saw an NPC reappear. This limits the amount of shared history the players can develop with a character, and is often a little unsatisfying as a result. So reusing NPCs helps prevent the narrative from fizzling out.

Secondly, re-using NPCs means they will have multiple facets relevant to the players. In our 9W game, Perseus’s family became a center of the narrative — each of the players was off doing something else, but they affected each other because their actions influenced Perseus and his family. So despite the characters being separated the players were still interacting with each other.

5. Have NPCs connected to each other and give them strong, contradictory opinions about each other. If everyone thinks Lord Bakersfield is a pompous asshole… eh, whatever. That’s fine. If some people think he’s a pompous asshole and other people think he’s the greatest man they’ve ever met (and they both have cause to think so), Lord Bakersfield is a much interesting character.

You’re also basically forcing the players (and their PCs) to make up their own minds about Lord Bakersfield. That means they’ll need to think meaningfully about him as a character, and that’s step one to memorability.

TOOLS FOR IMPROVISATION

Something that I talk about in Smart Prep is that if you’re looking to improve your improvisation, then you should prep tools that make it easier to improvise the stuff you find hard to improvise. What these things are is different for everybody: Some people find it hard to come up with cool names on the fly; other people find that trivial.

So which tools you find most useful is going to vary a lot.

NAMES: I put together a list of Fantasy Names by culling cool names I ran across in a data entry job and I’ve used that list over and over and over again in the last couple decades.

I recently prepped a name list for the Infinity RPG by doing a lot of research into real world cultures and their names, specifically to highlight the rich panoply of cultures found in the setting.

On a far more focused scale, Feng Shui 2 does something similar by distinguishing between characters from Hong Kong, characters from mainland China, and characters from Ancient China by using different methods of Romanizing Chinese names.

The globe-hopping Eternal Lies campaign very wisely includes a list of first and last names for each location the PCs go. Notably I did NOT follow the same practice in designing my Severn Valley expansion to the campaign because I felt confident in my ability to to improvise English names.

Over the Edge is another interesting example because Jonathan Tweet basically invented a set of naming conventions for the island of Al Amarja, subtly emphasizing the strangely akimbo nature of its place in our reality. I developed a cheat sheet of Al Amarjan Names to encourage GMs to lean into this. It can be found on Atlas’ official website.

MANNERISMS: Here’s a quick, one-stop shop: Maze Rats. It has a one page “Character Creation” sheet which includes random tables for appearance, physical details, costumes, personality, mannerisms, and hobbies.

You can get a lot of mileage by, say, randomly generating a part of your body and thinking about what you can do with it. If you have one of those dedicated hit location dice, here’s a really creative way you could use it.

AGENDAS: These are trickier to generate meaningful, high-quality random tables for, because they are generally going to be heavily dependent on the specific context of the game setting.

Assuming that your setting is already well-stocked with NPCs, however, one thing you can do is basically just co-opt an existing NPC’s agenda: In the real world, after all, there’s not just one guy who’s pro-Brexit or seeking to buy real estate in the Guildsman’s District or aligned with the Mafia or engaging in anti-android-apartheid activism.

So add this new NPC to one of these existing factions of interest. It works best to then give their agenda a twist so that it’s providing a different angle or insight into the agenda. The easiest twist is to simply flip the agenda and have them opposed to whatever the other NPC is trying to accomplish: So they’re anti-Brexit, trying to protect middle class property rights in the Guildsman’s District, a gangbuster, or an android-tester enforcing the apartheid.

KEEP A FILE: Something else you can do is to start keeping a file of cool NPCs you’ve seen in various adventure modules. I talk about this a bit in Strip-Mining Adventure Modules.

You don’t have to limit yourself to characters from RPG products, or even from the same setting or genre. A lot of the stuff that makes characters cool and memorable — their beliefs, their look, their mannerisms — all tend to translate well.

If these characters are a little too well known, this can be less effective. (Although, honestly, Ian McKellan’s Gandalf is basically an archetype at this point and it’s perfectly acceptable to have a wizard show up smoking a pipe, waggling their eyebrows, and speaking cryptically in dramatic whispers.)

Genre flips often solve this problem in any case: Use Gandalf’s mannerisms for a mafioso or Luke Skywalker’s characterization for a petulant halfling and your players will probably never even realize where you drew your inspiration from.

As Dominic finished, his eyes blazed with silver light. Rehobath was entranced. “It is the mark… It’s hard to believe that one of the Chosen should have come to me.”

This meeting between Dominic and Rehobath is a major turning point in the campaign.

Looking back on this moment now, it’s hard for me to imagine a version of In the Shadow of the Spire in which this doesn’t happen. But the truth is that if I ran this campaign another fifty times, the chances of this – or anything like it – happening again are basically nonexistent. Like “The Tale of Itarek,” this moment, and everything that comes from it, is the result of completely unanticipated player decisions building one atop another.

(If I actually did run this campaign again, of course, I might choose to restructure it to make including this material more likely. This is not out of the question. For example, the Severn Valley scenario I designed for Eternal Lies was similarly the unplanned result of very specific and relatively unlikely decisions made by the PCs. When I ran the campaign a second time, however, I added specific clues to make it more likely that the PCs would end up going there.)

So let’s take a moment to talk about how we got here. I think you’ll find it interesting, at least in part, because it also demonstrates how a number of different techniques I’ve discussed here at the Alexandrian can combine together in actual play.

Unlike most of these Running the Campaign essays, this one will contain SPOILERS for upcoming installments of the campaign journal. So you may want to skip it if you’d rather be surprised.

STAGE 1: ACTUAL PREP

In terms of actual prep (i.e., things I planned as the DM), there are basically two points of origin.

First, Dominic’s eyes. These were included in the campaign as one of the clues to the metaplot mystery of what had happened to them during the period of amnesia immediately preceding the beginning of the campaign. The notes describing the eyes were quite brief:

• If Dominic praises Vehthyl while wearing or holding the mithril holy symbol he woke with, his eyes become glowing silver globes with the following effects: +2 to Spot checks, detect magic, can be active for up to 15 minutes per level per day.
• A Knowledge (religion) check (DC 22) reveals that this is one of Vehthyl’s signs – it is a mark of the god’s chosen, indicating that they have taken the first step on the path to sainthood.

Second, Rehobath and his relationship with the Imperial Church. This gets a little more complicated.

Rehobath is based on Monte Cook’s Rehoboth. In the original Ptolus setting, Rehoboth Ylestos was the Emperor of the Church. When the Empire fell, Rehoboth fled to Ptolus, where his son Kirian Ylestos was the Prince of the Church, and “declared himself secular Emperor as well as the head of the Church of Lothian and set up his own Imperial court in the Holy Palace.”

Because I was transplanting Ptolus into my own campaign world, I had to figure out how to adapt that to fit with the gods, religions, and politics of the Five Empires. This went through several iterations, some of which were quite convoluted. (At one point, Rehoboth was theoretically being held in religious asylum and seclusion by his son, but the two of them were secretly working together as a nefarious conspiracy.) But at the time the campaign started it had settled into a more basic form:

• Rehobath (note the subtle name change, which I’m definitely claiming was deliberate and not a typo that iteratively asserted itself into all of my campaign notes) had once been the Gold Fatar of the Inner Cathedral of Athor. In the political wrangling around the appointment of the last Novarch (the head of the Imperial Church), he was effectively demoted to being the Silver Fatar of the Outer Cathedral of Athor in Ptolus.
• Aggrieved in his new position, Rehobath gathered power and eventually declared himself both the Novarch-in-Exile and Holy Emperor, claiming divine right of rule over both the Imperial Church and the Empire of Seyrun.
• Kirian Ylestos (who was no longer Rehobath’s son) had been sent by the Imperial Church to replace the heretic Rehobath as the rightful Silver Fatar of the Outer Church of Athor. He was successful in ousting Rehobath, who took up residence in the “Holy Palace” in the Nobles’ District.

Shortly after the campaign started, however, I realized that I’d made a mistake: It would be far more interesting to rewind the timeline and include all of that political finagling as backdrop events that would play out as current events in the Ptolus newssheets while the PCs went about their adventures.

So, at this point, Rehobath was still the Silver Fatar of the Outer Cathedral, although he was actively scheming to declare himself Novarch-in-Exile.

STAGE 2: PLAYER INTEREST

Once Dominic discovered that his eyes glowed silver whenever he praised Vehthyl, he became interested in figuring out why. Although it seems fairly obvious in retrospect, I had not anticipated that his interest would take the form of seeking out local Vehthylian religious experts.

I’ve previously discussed the method I used to respond to his interest in “An Interstice of Factions,” so you can check that out at length. But what it boils down to is that I gave him four different options:

When Dominic headed across the bridge into the Temple District, he made gentle inquiries into the worship of Vehthyl and discovered four options: First, the Order of the Silver God. Second, the Temple of the Clockwork God. Third, the Temple of the Ebon Hand. And, finally, an itinerant minotaur priest named Shibata.

This list was largely prepped by simply going through my notes and seeing which religious organizations and individuals in Ptolus were associated with Vehthyl. Although the Order of the Silver God (part of the Imperial Church) is included in this list, you might notice that Rehobath and his politics still aren’t present.

STAGE 3: UNINTENDED CONSEQUENCES

At Harvesttime, Dominic chose to speak with Shibata. He got some guidance and insight into what it means to be Chosen by one of the Nine Gods and what the religious mystery of Vehthyl was, but he ultimately wasn’t satisfied with the answers he got. So after mulling things over for a bit, in Session 14 he decided to seek more guidance at the Temple of the Clockwork God.

This actually came a bit out of left field for me as a GM: After seeking out Shibata, I hadn’t realized that Dominic was still thinking about looking for more answers, so I had never given any meaningful thought to what would happen if he went to the Temple of the Clockwork God. So I stalled:

The priest shook his head. “Why this should be or what your purpose is, I cannot say. And the wisest among us are not here. We would like to wait for their return and then pray for the guidance of Vehthyl. Can you return to us? Let us say in five days time, upon the ninth of Kadal?”

Basically, the five days of in-game time would give me some time to prep content that would meaningfully reward Dominic for pursuing this avenue of investigation. I knew that the Temple of the Clockwork God and another organization known as the Shuul were loosely aligned and that both of them venerated the Iron Angels. The Iron Angels are basically ancient fantasy mecha that were somehow related to the Lithuin Titans, and various ruined Iron Angels had been recovered in archaeological digs in recent years. (This is because Cook had used the name “Iron Angel” to refer to neutral outsiders related to the Iron God, but my setting already used that name for the ancient constructs and rather than giving the Iron Angels revered by the Shuul a new name, I decided it would be more interesting to have them simply revere my existing Iron Angels.) I knew that the Shuul had been reconstructing one of these Angels, and they and the Temple of the Clockwork God were interested in figuring out how to revive it (basically bringing what they perceived as a dead god back to life). I decided that Maeda, the head priestess of the Temple of the Clockwork God, would perceive the coming of the Chosen of Vehthyl as a sign that the time for reviving the Iron God had come.

I hadn’t done much more than put together a few fragmentary notes to this effect, however, when, as I discussed in Session 19, the group’s actions unexpectedly caused them to raid the Shuul’s headquarters. Given the timeline involved, it made sense that Maeda’s communications with Savane, the head of the Shuul, would be there and the PCs discovered it:

Brother Savane—

Brother Tannock has brought me strange news. A man bearing the Mark of Vehthyl has come to our temple. He is to return to us on the 9th of Kadal, at which time I shall see for myself. But if the Chosen of Vehthyl has come to us, then the hour has arrived. Can the Iron Angel be made ready?

Maeda

When I wrote the note, however, I hadn’t anticipated that the PCs would interpret it in the worst light possible. I thought it would be kind of a cool, enigmatic reference to the “Iron Angel” and then, when Dominic met with Maeda, there’d be a payoff when Maeda revealed what the Iron Angels were. (“Make it a mystery” is a technique described in Random GM Tips: Getting Players to Care.)

Instead, the note scared them: The Temple of the Clockwork God were conspiring with the Shuul and clearly had some sort of nefarious agenda where Dominic was concerned. Dominic resolved to skip his appointment with the Temple and was left figuring out where he wanted to turn next for answers.

STAGE 4: UNANTICIPATED CHOICE

At this point you might anticipate that Dominic would choose between one of the two remaining options he had found at Harvesttime: The Order of the Silver God or the Temple of the Ebon Hand.

Instead, he did something completely unanticipated: They had been briefly introduced to Rehobath during the Harvesttime celebrations at Castle Shard, and they made the decision to reach out to him directly as the local head of the Imperial Church.

So… what happens?

Well, I look at what I know about Rehobath and his agenda. And then I think about what he would do if the Chosen of Vehthyl basically fell into his lap.

The result, of course, is that the PCs are going to be thrust directly into the middle of Rehobath declaring himself the True Novarch of the Imperial Church.

And then things get even crazier.

SESSION 20C: DOMINIC AND THE SILVER FATAR

April 27th, 2008
The 8th Day of Kadal in the 790th Year of the Seyrunian Dynasty

Tee returned to the Ghostly Minstrel and described the entire encounter to Dominic.

Dominic was still uncertain, but Rehobath had seemed receptive and concerned… without the disturbing overtones of the letter they had found in the Foundry. Of course, the Reformists at the Temple of the Clockwork God had seemed nice enough, too. But Rehobath was giving answers… and Dominic was a priest of the Church.

“Will you come with me, Tee?”

“Of course!”

So the two of them quickly returned to the cathedral. Unlike Tee’s previous reception, they found themselves swept straight up to Rehobath’s office. He rose to greet them, but as Dominic meekly approached his desk the godwood suddenly flared to a bright light.

Rehobath stepped back, clearly shocked by the display. Fumbling his words for a moment, he suggested that they retire instead to the small seating area near the fireplace.

The three of them sat down. Rehobath, with an eager air, began by asking Dominic to show him the mark of Vehthyl. Dominic with a nervous, sidelong glance towards Tee murmured a prayer to Vehthyl:

Mighty, majestic, and radiant,
You shine brilliantly in the evening,
You brighten the day at dawn,
You stand in the heavens like the sun and the moons,
Your wonders are known both above and below,
To the greatness of the Magus,
To you, Vethyl, I pray!

As he finished, his eyes blazed with silver light. Rehobath was entranced. “It is the mark… It’s hard to believe that one of the Chosen should have come to me.”

Dominic had many questions, but there was much Rehobath didn’t know: Although he could confirm that Maeda was the “head priestess” of the Temple of the Clockwork God (confirming Dominic’s suspicions regarding the letter), he had no idea what the “Iron Angel” she mentioned in her letter might be.

However, Rehobath was able to confirm that Maeda had formed an alliance with the Shuul, who were led by a mysterious man known as Savane. The Shuul had apparently constructed most or all of the Temple of the Clockwork God.

Dominic was most interested, however, in knowing about what had happened to him. How or why had he been chosen by Vehthyl?

But, as Rehobath said, “The ways of the gods are filled with mystery… Vehthyl perhaps moreso than all the rest. To be chosen by them is to have your life placed in the focal point of creation. There is no way of knowing why you were chosen – only that, because you were chosen, you are an important person in an important place at an important time.”

This didn’t do much to give Dominic the guidance he was looking for, but then Rehobath said, “We may not know why Vehthyl has chosen you, but I suspect I know why you should have come to me now.”

“I was once the Gold Fatar of Athor. I served on the Council of Councils and was esteemed. When the last novarch died, it was clear to many that I was destined to follow him – to speak as the Living Voice of the Nine Gods. But when that time came, the Emperor played politics.” The last word was filled with venom. “Another was named in my place while I was stripped of my offices and sent here to serve as the Silver Fatar of an outer cathedral. It was the most blatant interference by the Emperor in the matters of the church since the Years of Heresy.”

Historical Note: The Years of Heresy began in 615 YD when the Emperor of Seyrun became the leader of the Imperial Church and called for a Time of Reflection. It later became known as the Purging. For five years a bloody, internal war was waged against heresy cults. When the Emperor was assassinated in 620 YD, church and state became separate once again and the Time of Reflection came to an end shortly thereafter.

“I believe that you can help me, Dominic. I believe that you were meant to help me.”

“What do you want me to do?” Dominic asked.

“Simply to let yourself be known. Your presence here in Ptolus is a sign. I would like to call a convocation in, let’s say, two days. Could you return here on the 10th?”

Dominic was hesitant, but he agreed. Rehobath then summoned in several members of the Order of the Silver God. The Order were the primary scholars of the Church here in Ptolus, and Rehobath wanted them to examined Dominic carefully and confirm the veracity of the mark. This they did – not only observing the glow of the eyes, but also testing its various properties (most particularly its ability to detect magical auras). When they were satisfied, priests escorted Tee and Dominic in honor to the front doors of the cathedral.

NEXT CAMPAIGN JOURNAL

The 1st Edition of Vampire: The Masquerade was supposed to be “a storytelling game of personal horror.” That was literally the entire back cover text, except for a quote from Günter Dorn‘s Das Ungeheuer Darin (a fictional work). Early in the book, Mark Rein*Hagen writes:

This storytelling game provides a way to experience a terror of an all too immediate nature, for it allows you to experience the horror from the other side of the mirror. The horror of Vampire is the curse of what it is like to be half-beast and half-angel, trapped in a world of no absolutes, where morality is chosen, not ordained. The horror of Vampire is the stirrings of the Beast within and the cravings for warm blood. Perhaps the greatest risk of playing Vampire is seeing yourself in the mirror. To play this game, you must bear witness to the madness within you, that which you strive to master and overcome, that which you cannot bear to face.

Why, then, in actual practice did the game so often manifest as “katanas & trenchcoats” — a style of play that others have described as “superheroes with fangs”?

This shift in focus seemed to happen despite the best intentions: Vampire players were all about the “personal horror” and “it’s an immersive storytelling experience, not a combat simulator” selling points of the game. They strongly self-identified with those values. And yet their games would somehow still often end up being katanas & trenchcoats.

In some cases, of course, this style of escapism was simply more appealing to the players; the vampire as a cool and enigmatic avatar was more fun than the vampire as a form of self-reflection on the nihilism of morality and the fragility of humanity. But if this were the fundamental issue — that the appeal of escapism will necessarily override an RPG’s intended style of play — then you would expect to see this be more or less universally true.

And it isn’t.

Take, for example, Call of Cthulhu. Here is another popular, widely played horror game which emphasizes a shift away from the D&D-style “combat simulator,” featuring characters whose humanity and sense of identity is steadily eroded by their exposure to cosmic, uncaring, inhuman truths. But even in the case of Pulp Cthulhu, which deliberately seeks to blend that style of play with a sort of Indiana Jones savoir-faire, it still appears to be passingly rare for “shotguns vs. Cthulhu” gameplay to emerge.

Why?

Well, there are a number of factors that probably contribute. But the title of this essay probably gives away the fact that I think it largely boils down to the game structures (or lack of those structures) supporting the desired style of play in both Vampire and Call of Cthulhu. Because, as I’ve noted in the past, players gravitate towards structure.

It’s easy to simplify this down to, “Call of Cthulhu has a Sanity mechanic!” And then people say, “But Vampire had a Humanity mechanic!” But this is, in fact, an over-simplification because it fails to look at the game structures that were built around those core mechanics.

HUMANITY vs. SANITY

At first glance, Humanity and Sanity seem similar: Both are numerical meters. Over time, characters lose them. When the meter runs out, the character is permanently “broken” in a way compatible with the overriding theme of horror in each game and can no longer be played as a PC.

In the case of Vampire, however, although a small grab bag of mechanics were based on the character’s current Humanity score, virtually no structures were built around the loss of Humanity. The Degeneration mechanic (which didn’t even have a name in 1st Edition) was something that the GM was supposed to trigger more or less by fiat when the PCs took certain types of actions.

Superficially, this once again appears identical to Call of Cthulhu‘s Sanity mechanic. Here, too, the GM is supposed to trigger a sanity roll whenever a certain condition is met during play. So what’s the difference?

Look at all the game structures in Call of Cthulhu built around the Sanity mechanic: Every creature you face triggers a Sanity check. Virtually every grimoire of forbidden knowledge you read triggers a Sanity check. And the game also has a very specific default scenario hook which is, “Go investigate strange creatures and grimoires of forbidden knowledge.”

So basically everything in Call of Cthulhu is built around the Sanity mechanic. By contrast, Humanity is just off in a corner twiddling its thumbs.

Furthermore, as you lose Sanity in Call of Cthulhu you become more likely to fail your sanity tests. It’s a path of accelerating decay that ends in madness. Vampire, on the other hand, utilized a “hierarchy of sin”:

• Humanity 10: accidental wrongdoing
• Humanity 9: any sort of purposeful wrongdoing
• Humanity 8: shoplifting
• Humanity 7: theft and robbery
• Humanity 6: unintentional killing
• Humanity 5: wanton destruction
• Humanity 4: causing injury and personal harm
• Humanity 3: sadism and perversion
• Humanity 2: murder
• Humanity 1: the most heinous and demented acts

If your Humanity has already fallen below the point where a particular type of act is considered a “sin,” then you no longer have to make checks for it. The system is literally designed to plateau your character at a Humanity score equivalent to whatever style of play you prefer and then stop calling for Degeneration checks.

So not only was the system not supported by structures that would make it a central pillar of play, it was actually structurally designed to remove itself from play entirely.

And that’s why Call of Cthulhu remains focused on its existential horror and Vampire… doesn’t. It’s not designed to.

Go to Game Structures

This will start off with a bit of a quick review of the advantage/disadvantage system, so feel free to skip down a bit if you’re already thoroughly familiar with that.

In 5th Edition, various circumstances and abilities grant either advantage or disadvantage to a character attempting an action: If you have advantage, you roll 2d20 and keep the higher result. If you have disadvantage, you roll 2d20 and keep the lower result. If you have both advantage and disadvantage, they cancel out (and you just roll 1d20). And they do not stack (so no matter how many things are giving you advantage, for example, you still only roll 2d20 and keep the highest, not 3d20 or 5d20 or 10d20), which also means that even one factor granting advantage will cancel out any amount of disadvantage (and vice versa).

There are several benefits of the advantage/disadvantage system compared to giving circumstantial modifiers to the die rolls:

• The modifiers you’re rolling against are not in constant flux, reducing the amount of in-game calculation required.
• It is viscerally pleasing and immediately rewarding to roll 2d20 and take the higher/lower result. It’s fun to do and you can literally see how your advantage benefited you or your disadvantage cost you by looking at the result on your gained/discarded die.
• It helps maintain the “bounded accuracy” of the system; advantage helps you, but you can still only get die results of 1 to 20.
• “Advantage” and “disadvantage” are incredibly useful terms of art, which designers, scenario writers, and DMs can quickly and efficiently use for any number of purposes. For DMs, in particular, they provide a very simple way to make a fast ruling.

The reasons for not allowing advantage or disadvantage to stack are:

• To maintain the simplicity of that fast, efficient DM’s ruling. Once you’ve determined that something in the situation grants advantage, for example, you don’t have to keep thinking about all the other things that might grant advantage: You have advantage. Move forward. Roll the dice.
• You don’t need complicated stacking rules, nor do you need to allow abilities to stack in potentially absurd ways. This removes one vector by which an RPG system filled with myriad options can suddenly break from the unexpected combination of those options.
• There are some mathematical effects of allowing advantage to stack multiple d20’s into a single roll, the most notable of which, in my opinion, is that your percentage chance of scoring a critical hit radically expands. (This last point is debatable, however, as many would argue that this is perfectly reasonable if you’re enjoying a massively advantageous situation. It also only applies to actually stacking additional dice, but not to the scenario in which you stack all advantage and all disadvantage and then compare the totals to see whether advantage, disadvantage, or neither applies.)

This system has one additional advantage (pun intended) that I want to call specific attention to: The simple, clear-cut mechanical concept of “advantage” also encourages players to engage creatively with the game world in order to create fictional positioning that grants them advantage.

Another example of this that I’ve seen in actual play is Numenera‘s concept of an “asset” — on any given task, PCs can have up to two assets, each of which shifts the difficulty of the task by one step. The first asset “slot,” so to speak, is often occupied by having the right tool for the job. The second asset slot is usually dependent on having some sort of advantageous situation in the game world, and this naturally results in players seeking to create those in-world circumstances that will give them an asset on a task.

In both cases, the clear-cut term of art coupled to the specific fictional situation in the game world reinforces the fiction-mechanics cycle. The mechanic thus, almost paradoxically, encourages players to engage in the game in non-mechanical ways: It’s not enough to just “play your character sheet” by saying “I hit the orc with my +6 attack bonus,” because the mechanics are no longer confined to the bonuses on your character sheet.

Arguably, of course, you can get the same benefit from any system that allows GMs to assign situational bonuses and penalties. But in actual practice, the clear-cut mechanical concept with a term of art attached to it provides a common framework. People just talk about and think about “advantage” and “assets” in ways that they don’t talk about and think about a miscellanea of +1, +2, or +5 bonuses.

THE PROBLEM

Speaking of actual practice, however, this final — and arguably most important — aspect of advantage tends to frequently disappear at the table.

The problem, ironically, is the very versatility of the system. Because advantage is such an easy mechanical hook to use, the designers of the game have used it to model all sorts of things. It’s hard-coded into everything from class abilities to spells to magic items. For example:

Dwarven Resilience. You have advantage on saving throws against poison, and you have resistance against poison damage (explained in Chapter 9).

Or:

Beacon of Hope. This spell bestows hope and vitality. Choose any number of creatures within range. For the duration, each target has advantage on Wisdom saving throws and death saving throws, and regains the maximum number of hit points possible from any healing.

Or:

Boots of Elvenkind. While you wear these boots, your steps make no sound, regardless of the surface you are moving across. You also have advantage on Dexterity (Stealth) checks that rely on moving silently.

Because advantage doesn’t stack, however, tension is created between the designer’s utility and the DM’s utility: If a character has hard-coded advantage from equipment or racial abilities or whatever, the DM immediately loses the ability to meaningfully model the game world through advantage and the player is simultaneously discouraged from engaging with the game world in order to create favorable circumstances.

This is not a desirable outcome: Basically every time the game hard-codes advantage in this way, it makes the game less interesting in actual play.

Numenera recognizes the same basic problem, which is why it provides two asset “slots.” The solution is not quite so straightforward for 5th Edition because there are so many pieces of equipment, for example, that provide identical forms of advantage, that simply providing two slots will simply create min-max builds that stack multiple advantage and still shut down situational creativity (because both slots will already be filled).

But we can find a solution, I think, through parallel thinking. And by simply cutting straight to the heart of the matter.

SITUATIONAL ADVANTAGE

Situational advantage is any advantage which is derived from a character’s immediate circumstances; particularly and specifically those cases of advantage resulting from characters taking actions or positioning themselves in order to create specific situations which grant them advantage.

Situational advantage, and only situational advantage, stacks with other advantage:

• If you have hard-coded advantage (e.g., the advantage against poison damage from dwarven resilience) and situational advantage (e.g., the character manages to dilute the poison before being forced to swallow it), then you roll 3d20 and take the best result.
• One source of disadvantage can cancel EITHER all hard-coded advantage or all situational advantage, but not both. (So if you have all three, you’d still have advantage and roll 2d20 while keeping the best result.)
• If you have two or more sources of disadvantage, then they will cancel both hard-coded and situational advantage. (You would simply roll 1d20 and resolve the action check normally.)

Note that not all forms of advantage appearing in the rulebook are necessarily hard-coded. Some describe situational advantage. (The optional rules for flanking, for example.)

What about advantage from spells? Is the advantage provided by a spell situational? There is a potentially simulationist argument that they are (or perhaps that some subset of them are, although that way probably lies madness). But the primary meta-game point of all this is to encourage players to think creatively as they engage with the game world instead of just throwing a prepackaged block of mechanics at a problem.

And a spell, after all, boils down to a prepackaged block of mechanics.

So if I had to make an ironclad rule, I would say that advantage from spells is always considered hard-coded advantage.

Fortunately, the entire point of situational advantage is to prevent hard-coded rules from disempowering the GM. So I will by happy to override this ironclad rule whenever players think creatively in order to create situational advantages from their spells. For example, by using a create food and water spell to water down the poison before it’s fed to the dwarf.