Optional D&D Roleplaying Rules for Compulsions

I came up with these rules awhile back, as a way to help me roleplay some of my own characters, and recently put them to use for the first time in a session and they worked great. So I'm going to explain the rules, and then talk about how that session went.

For characters that are supposed to be affected by compulsions that make them want to behave in ways that are incompatible with their moral code or who they see themselves as, which are supposed to be difficult but not impossible to resist, it can be hard to figure out a way to properly represent these in-game, if you want more guidance than simply roleplaying the effect yourself. This can be especially problematic when the effect is assigned by the DM to a PC, such as when a magical effect causes a PC to gain a new flaw.

For simple, immediate impulses, making a Wisdom saving throw (DC set by PC) to resist the urge to immediately do a thing could be appropriate - eg, while a hungry vampire is hugging a living humanoid, they might make a Wisdom saving throw and on a failure make a bite attack against the person they're hugging. Similarly, if an alcoholic has a cup of alcohol in front of them, they might make a Wisdom saving throw or take a swig.

However, for actions that take multiple rounds, and especially ones that take planning, it's a lot harder to represent them with a single Wisdom saving throw. Eg, for an alcoholic who doesn't happen to be right next to an alcoholic beverage, how would you represent the process of them going to a bar, ordering a drink, and drinking it, despite their desire to quit drinking?

In 3.5, many of these effects are represented by ability damage - the Book of Vile Darkness has ability damage due to withdrawal from addiction, and the Libris Mortis has ability damage for undead with an unfulfilled desire or need to feed on the living. However, this has always felt unsatisfying to me. For addictions, it's quite plausible that a character could go into withdrawal, become incapacitated, and then recover, without ever feeling like you might not be able to prevent your PC from seeking out their addiction. Libris Mortis has the Inescapable Craving type of undead hunger result in uncontrollably seeking out the object of their hunger if they reach 0 Wisdom, but it's no harder for a wraith at 2 Wisdom to resist draining life than a well fed wraith. And for Diet Dependent undead, this clause only takes effect at a point at which they also lose the ability to move, creating a similar issue to drug withdrawal rules.

So, here’s my suggestions for how to go about representing an eroding will to not do multi-step activities your character feels compelled to do.

First, one option would be to do a Wisdom saving throw for each step, increasing the DC progressively with each failed save. For example, the alcoholic in withdrawal might have to do a Wisdom saving throw to determine whether they walk home past the bar, or choose a different route to avoid passing the bar. On a failure, they walk towards the bar, and then when they are about to pass it, they must make another Wisdom saving throw or enter the bar. They then proceed to make another Wisdom save or order a drink, and another Wisdom saving throw or drink it. Then they make another Wisdom save vs ordering a second drink, and so forth. This continues until they’ve either made it back out of the tempting situation, or drunk themselves to unconsciousness, or if something causes another urge to be stronger than the urge to drink (eg, if the bar catches fire, the urge to avoid burning to death will supersede the urge to keep drinking).

For a vampire, a similar sequence might look like first going to a popular place to meet a one-night stand, choosing a target, flirting with the chosen target, charming the target, getting the target alone and biting the target. Or whatever hunting strategy would most fit with that vampire’s character and/or prior history. Unlike the alcoholic ordering a drink, the vampire luring a one-night stand to bite has a potential to fail despite the vampire’s best efforts (e.g. if the target succeeds a save vs vampire Charm, or the vampire fails a Persuasion check along the way). In that case, the failure could elicit another Wisdom save vs the urge to try again (possibly on a different target).

Another option would be to represent the character’s will to not do the thing they want to do as a set of arguments against doing it. For example, the alcoholic might have a list like:

• I’m risking liver damage

• My ex-wife won’t let me see my kids if I can’t stay sober

• I got fired from my last job for showing up drunk, and I want to keep my current job

• I’d like to have money to spend on things other than booze

• Getting drunk makes it easier for the assassins hunting me to potentially kill me

Then the PC ranks each of those reasons from most to least important for this character. When they feel a craving, they must make a Wisdom saving throw, and on a failure, they negate one of those reasons. For example, the alcoholic might decide that the other things they could spend their money on aren’t as worthwhile to them as getting drunk, or that they don’t really care about their liver’s health, or that their ex-wife will probably find some other reason to keep them from seeing their kids. This counterargument doesn’t have to be, and probably shouldn’t be, something a rational person would consider a good argument, but it’s one that feels compelling to that character, and pushes them closer to being willing to drink alcohol.
With either option, if the character satisfies their craving, they could revert to their initial state of being totally unwilling to satisfy their craving ever again, along with feeling really unhappy about their recent actions. Conversely, you could combine the two options by having them make saves against action sequences during a craving, and then upon satisfying the craving, make a save against losing a reason to not indulge the craving in the future. Each lost reason makes the DC against the first step of the action sequence harder in the future.
And now, how I put this in practice!
This takes place in our Westmarch-style D&D campaign where adventurers spend their downtime in a Planar City created by a silver dragon archmage. One of my PCs, Xalith Baenduis, is a drow who has been partially ceremorphosized, or turned into an illithid. (She's an aberrant mind sorcerer.) She's not illithid enough to actually need to eat brains, but she's illithid enough to feel a desire to eat brains, and due to a homebrew feat, she can also regain spent spell slots by eating brains. Meanwhile, I came up with the following list of reasons she doesn't want to eat brains (the numbers reflect the importance ranking):

• It's gross. (#5)

• I worry that acting more illithid-like will eventually make me lose my identity to the tadpole. (#1)

• I'm friends with a githyanki who would be horrified by this behavior if she found out. (#2)

• I might get kicked out of the Planar City if I'm seen as a threat to the other inhabitants. (#3)

• The illithid might have an easier time finding me if they hear about brainless corpses being found. (#4)

Xalith and another PC of mine, a yuan-ti pureblood named Zsistla, were hanging out in Baldur's Gate, in a walled ghetto known as Little Calimshan, trying to deal with Zsistla being blackmailed into kidnapping a Calishite jewelry merchant to appease someone who caught her stealing a large sum of money from a merchant. Unfortunately, Xalith, as a drow, sticks out in Little Calimshan, and while they were trying to sneak around the neighborhood late at night, she got noticed by some thugs who decided to escort her out of Little Calimshan. She responded by trying to twin spell charm person, they both succeeded their saves, and a fight ensued.

Cut ahead several rounds. Xalith has successfully removed one opponent from combat using calm emotions, then ran around a corner and knocked the other opponent unconscious, but she knows reinforcements are coming. I considered fleeing with or without the unconscious goon. Without would be easier, but if she brought him with, she might be able to eat his brains. Cue a Wisdom save. I arbitrarily set the base DC to 12, and Xalith failed, so she proceeded to levitate while carrying the unconscious goon, hiding on a rooftop with him.

Next round, another Wisdom save failed, so Xalith takes out her dagger and tries to open his skull, but utterly fails. Rinse & repeat for another round. On the third round, with reinforcements getting closer, and her not very well hidden (I rolled badly on nearly every Stealth check Xalith made that whole session), she finally succeeds the Wisdom save and abruptly decides that no, she does not in fact want to eat this guy's brains, she wants to GTFO now.

She regroups with Zsistla, and we try and utterly fail to kidnap their target, and then decide to go hide somewhere and rest for 4 hours (long enough for a short rest for Zsistla and a long rest for Xalith, since we've interpreted the trance racial feature as allowing 4 hour long rests). Unfortunately, we come out of our hiding spot to find we're surrounded by goons, led by Rilsa Rael, an NPC the DM took from the Murder at Baldur's Gate premade adventure. There's far too many for us to fight, so when Rilsa Rael decides to start asking questions, Zsistla spills the beans.

Turns out Rilsa Rael is willing to team up with us to double-cross Zsistla's blackmailer, so we happily agree - we were intending a double-cross anyway, and allies make that double-cross much safer. Part of the agreement is that we should lead Rilsa to where we stashed their missing goon. Miraculously, it turns out that he survived, and Xalith silently feels deeply relieved that she didn't have to try to explain (to both Zsistla and Rilsa) why the guy's head was cracked open and his brains eaten. The rest of the session goes smoothly, and we finish off with a blackmailer defeated, some information for Zsistla about his connections and motivation, and Rilsa as a friendly contact willing to give us a favor sometime because we helped her deal a serious blow to a rival gang the guy was affiliated with.

Xalith hasn't actually eaten a brain yet, so I didn't have a chance to see if she decided brain-eating isn't actually gross at all. But I've seen benefits to both parts of the system, now.

As a character-building exercise, figuring out all the reasons why Xalith doesn't want to eat brains gave me a much clearer sense of her personality. Note, for example, that moral objections aren't on the list, because she's chaotic evil. But the fact that fear of becoming more illithid is number 1 has clarified for me that in general, Xalith is deeply afraid of losing what shreds of her identity she's managed to hold onto so far. The fact that her memories of her previous life are full of gaps, her trance now involves visions of eldritch vistas with a giant elder brain (Ilsensine), and her instincts are different now worries her, and the thought of changing even further absolutely terrifies her. This tells me a lot of stuff that's useful to understanding her even when she's not craving humanoid brains.

And in actual play, figuring out component steps and rolling a Wisdom save for each one really helped me create a scene where she almost succumbs to the urge and then catches herself. In that situation, the steps I had in mind were a) bring the goon somewhere private, b) open up his skull, and c) eat his brain. So, she could have succeeded in shaking off the urge at any of those steps, and since she failed step b) several times, she got several tries at it. If I had actually rolled better than a 5 on my dagger attacks with advantage, though, I could have gotten his skull open. At which point, would she have actually eaten his brain? I'll never know. I know I loved the uncertainty of not actually knowing if she'd be able to stop herself from eating his brains, and I loved how the failed saves, failed attacks and finally successful save created a story of almost succumbing to temptation that I probably wouldn't have been able to come up with on the fly by myself.

I did forget about my intention to increase the DC with each failure for a point of no return, but it didn't actually matter, because my successful save was well above the cutoff.