Them Bones of Adventuring - XXV: Stealth Revisited

An ongoing exposition on table procedures for common exploration feats and rules, which began here with part one.

Introduction

Though for the most trivial of sweeps a simple stealth check can be everything a situation calls for, the books leave any mincing past that completely up in the air and each referee to fend for himself. A system to arbitrate the use of stealth can be, much like the act itself, a tiptoeingly minor but important part of the game, and one to unexpectedly punch above its weight, tending as it does to present a way for players to jump the script fencing and avoid, among other things, combat. And we all know how the more modern shades of DnD design are ever so anxious that a player should not be able to “skip content”.

My initial belief that stealth merited more gradation than that found in a single roll saw me making the wrongheaded departure in the direction of calling for rolls every single turn, thinking this was going to bring about anything of interest beyond failure. Engaging the superpower of hindsight, it is easy to see the previous attempt to tackle this standing as somewhat naïve, for even highly skilled sneaks will be bound to statistically falter in the face of reiterated rolling (and with casuals standing less of a chance than a yakuza’s pinky) as well as recognizing that having different speed settings to the stealth approach made for nothing but an illusion of choice, as a player will simply always default to the one he’s most confortable with (typically the slowest) and edge out the rest, this working against the abstraction as well given that attempting stealth ought to be something that a character is presumed to engage in to the best of his ability at all times, rendering choices of “speed vs. silence” as pretty much moot by design in all but the most rarified of cases.

Crouching Tiger, Hidden Complexity

To call back the earlier post, stealth is one of those areas of play where the thing's decisiveness can prove stifling, pointing to rules that suffer from being excessively abstracted. A practical approach will require something sensible, able to neatly tie off a number of disparate situations, preferably without cutting down player agency and remaining easy to ascertain at the table on the back of as little refereeing discretion as possible. To this end I am now inclined to favor a one-roll-and-done mechanic that quickly frames a scene and leaves the rest in the hands of the player.

Considering these four typical situations that need to be accounted by stealth rules:

1. Characters employing stealth to move up to or past a fixed position

2. Characters sneaking up on a moving target or tailing it from a distance

3. Use of Stealth in Combat

4. Ambushes

I'm casting for something that will allow those less furtive a chance to literally get by while still presenting an optional layer of challenge for characters who wish to aim for a correspondingly greater prize. Past resisting the temptation to demand multiple rolls one must equate that stealth can both be used for avoidance as well as to pave the way to a potential attack, as settling for the variance inherent to a single roll (plus a to-hit roll) has to prove enough to ensure an assassination attempt is kept an uncertain prospect at best. Finally, simplification also dictates that Stealth should be a roll against a static total, to be applied to PCs and NPCs alike, the opposition’s Passive Perception being the obvious clean fit.

Muting Sound, Eluding Sight – Rethinking the Sensory Distance

Abstractionwise stealth typically faces the problem of dealing with either the sight or the hearing of the opposition (or, panning out this thinking, the senses of smell or touch for certain creatures), it being highly situationally dependent which one is to take precedence. Regarding human perception, highly attuned to motion as it is, the notion of stealth is pretty much dependent on ruling out the visual – being a given that a character will need to be out of sight, disguised, immobile or all three – and pinning the variable on sound by default. This means the opposition is already implied to be with its back turned, looking the other way or have its sight obscured for the standard Stealth attempt to even happen.

For simplicity’s sake, no matter a creature’s sensorial mainstay, its awareness threshold is always represented by a partially adjudicated, partially randomized distance based on a reverse engineering of the random encounter distance: its sensory range, rolled as 3d6 x 10’.

Any character – even one on sentry duty – will inevitably display an uneven level of competence and concentration at any given moment, as tiredness, momentary distraction and sheer boredom all take a toll that the referee translates as a rolled total representing three concentric (but non-overlapping) fields of sensorial awareness, prosaically called Long, Medium and Close distances, each representing a liminar point at which Stealth becomes more difficult to maintain.

The sensory range is segmented into the different thresholds by ordering the three d6 results from highest to lowest, meaning that, for example, a roll of “2,5,4” translates into a sentry with a 110’ total sensory radius of which the first 50’ (110’-60’) are considered “Long” and thus traversible on the back of a simple successful Stealth check, the next 40’ (60-20’) are considered the “Medium” threshold and the last 20’ are considered “Close”, each implying a DC increase; By resorting to this segmentation, we know that a character attempting a backstab would need to have a roll beat three consecutive DC increments but those wanting to simply bypass a guard post could make do with just the basic check or even none at all, depending on the terrain’s configuration, happenstance and actions taken by the players to effect a distraction, for though Stealth is a lonely business best left in the hands of specialists a canny party ought to get itself across a wide range of situations by relying on a frontrunner to run some interference and facilitate the rest of the pack’s journey.

The Crunch

Stealth Procedure

0. The possibility of Stealth

- A player prompts the referee to rule if a character can feasibly hide or attempt an approach under stealth.

1. Situation and modifiers to the Stealth check are determined

- Referee points out any salient challenges presented by the situation that the character can perceive (such as the defender’s field of vision, randomized or otherwise).

- Player tallies up any modifiers from Dexterity and training in Stealth as well as possible constraints in terms of equipment load affecting the character.

- A sketched outline of the terrain may be requested, if it is deemed relevant. 

2. Character’s Stealth attempt is rolled (along with the defender’s Sensory Distance)

- Referee secretly rolls 3d6 and a d20 for the character's stealth (or more, if the character benefits from Advantage or multiple characters are attempting to move under stealth), ordering the three d6’s into the defender's sensory tiers.

- The sensory distance emanates from the closest defender, the stealth DC being provided by its passive Perception score (or the highest score present, if unclear).

- Once challenged, the rolled Stealth either fails to beat the DC and the character draws notice or the attempt succeeds and movement proceeds undetected.

- Note that no matter how weak the rolled attempt, any consequences of failure are only triggered if and when the character crosses into the sensory threshold proper, a distance that – it merits repetition – is not known to the player.

- Fumbles immediately give away the character's exact position to the defender, granting him the Initiative. 

3. Player input

Far from being a completely mechanical process, the player is encouraged to use available maneuvering space in whatever way possible to better his position, be it through use of cover (visual or aural), moving to skirt the enemy’s senses or arranging a distraction.

- Past the initial check and as long as the character doesn’t take actions that’ll draw undue attention, the player is free to dictate the character’s movement and take slow measured actions within the enemy’s sensory range.

- As the character decides to move and a closer sensory threshold is breached the previously successful result is again measured against the increased DC, then being allowed to ride on if it remains successful or the character being detected if it fails to measure up.

- If a stealthing character is hidden by cover at the point a threshold would be passed then the increase to the check’s DC is delayed until such a time as the character emerges from behind it. If cover is used to fully bypass a threshold then the character becomes exempt from the difficulty increase for that threshold.

- While within the enemy’s sensory distance, a character that takes any sort of action carrying a risk of detection or is faced with a drastic enviroment change, be it noise or movement-wise, may have his Stealth check confronted with hostile Perception checks.

For example: a party’s advance scout is following an enemy warband through a tangle of forest trails when suddenly a clearing carpeted with dry leaves is reached. Now, to keep track of the quarry, the scout must decide if he risks detection by crossing the clearing while still within earshot of those being followed – prompting a public Perception roll from the opposition – or if he allows the group to move away in hopes of catching them at a later point, keeping the current Stealth value being used but at the risk of losing track of the foe.

The archetypical situations

Though this is a truism applicable to almost all facets of the game, the open-ended nature of stealth begs one to repeat that, depending on player ingeniousness, particularly complex and well thought-out approaches may obviate the need for rolls on each of the following.

Approaching a fixed point under stealth

The standard situation, often relying on tactical use of terrain and thence a defined/sketched environment.

- Depending on the actual circumstances, the character will move at a rate from between half normal walking speed down to a crawl of just 5’ per round.

Shadowing another character

Concealed or disguised movement in close pursuit of another within a complex environment that defies a clear distance positioning, such as a network of tunnels or a city’s streets.

- Stealth is rolled as normal but sensory range is witheld, as distance is assumed to expand and contract in a fluid manner as the parties’ course unfolds. Instead the sensory range is left unrolled and stealth thresholds are passed as the player declares that he wishes to move closer.

- Once determining hard distances becomes important (i.e. someone wants to use a ranged weapon or a character gets caught) the potential gap of the sensory distance is rolled and resolved into the concrete encounter distance.

- A character shadowing another generally moves no faster than a walk (normal movement speed).

- Attempts to open but discreetly follow another through an urban environment rely on Wisdom rather than Dexterity.

Mounting an ambush

Requiring favourable conditions to be an option, ambushes invert the logic of the standard attempt, as the concealed character becomes the fixed point and the quarry is the one approaching.

- Roll the foe’s sensory distance as normal; the Stealth check is made with Wisdom instead of Dexterity; as the enemy pointsman approaches, so rises the likelihood that the ambusher will be spotted.

- If a small group of characters hides hastily each rolls individually as usual but if they’ve had time (10 minutes) to prepare a planned ambush then the character with the highest stealth potential (Wisdom plus Stealth training) can make a single roll at Advantage to prime the entire group.

Combat

Stealth in combat isn’t about definite concealment but rather about seizing an opportunity to blindside foes for just long enough to escape or deliver an unexpected blow. The abstraction of the sensory range isn’t used, as mutual awareness is assumed by close proximity.

- Disappearing in the midst of a melee after having been noticed is exceedingly difficult and requires a rare set of occurrences to pull off, needing not just cover but also a window of distraction from potential witnesses to slip away, such as the enemy targetting a different character with missile attack or being already engaged in melee combat.

- The check to engage in stealth still needs to beat the foes' highest passive Perception score, as the hostiles being distracted only permits stealth to be attempted in the first place. In certain complex combat situations, the hectic pace and limited communication possibilities may make it possible to hide from just some of the members of an opposing side.

The Sensory Thresholds

The abstraction of the distance tiers is not only meant to translate purely into terms of distance but also represent how off-guard a target will to be caught the moment a character approaching under stealth decides to reveal himself.

- Long tier (the defender’s edge of aural perception, generally given as 3d6 x 10’), Stealth DC = defender’s Passive Perception

This triggers the basic stealth check and beating it will usually provide enough leeway to skirt around a roving patrol, bypass a sentry post or follow a target from a discreet distance. Failing at this point means there's a chance a character might get spotted (see the post's last header) as the sensory radius is entered and Initiative be rolled to see how the situation unfolds, though by dint of distance things might not necessarily evolve into a combat.

- Medium tier (gotten by subtracting the highest die from the 3d6 pool rolled), DC increases by 1

By slinking into this tier, a character is able to line up a shot with a missile weapon without distance penalties and, if the character (or the majority of a party) spring an attack from this distance they’ll have Advantage when rolling Initiative.

- Close tier (gotten by subtracting the highest remaining d6 from the above pool), DC increases by 1

This distance lends itself to melee combat as well as the use of thrown weaponry, characters that reveal themselves from this tier automatically win Initiative and roll a contested check to determine if the target is surprised.

- Assassination (directly adjacent to the target) DC increases by 2

If this point is reached the ultimate prize is at hand, as the character will be ensured of having both Initiative and Surprise, and may attempt to deliver a killing blow with a melee weapon.

Selective Silence – circumstancial caveats to the Stealth procedure

Between the quality of the opposition and the many facets of an environment able to influence a Stealth attempt a single post cannot hope to cover all the happenstance a referee might have to represent in the course of play, so here's the costumary set of general rules of thumb:

Character’s equipment constraints

- Being encumbered will mean Disadvantage on the check.

- Inventory slots filled past those classed as fast-access increase the roll’s fumble margin and so does wielding a weapon of unusual size or configuration (i.e. a flail or anything requiring both hands).

- Wearing an armour type that limits the input from the Dexterity modifier to AC likewise extends such limitation to all physical checks, including Stealth attempts.

Defender’s situation

To model situations where differences in the defender’s perception are a significant factor, such as when dealing with creatures with exotic senses or whose attention is sharpened or dulled can be done by modifying the amount or size of the dice rolled for the sensory distance, with additional dice implying additional sensory thresholds and viceversa.

Example: sentries posted at the gates and certain tents of a military camp can be adjudicated as being particularly alert, rolling 4d6 and dropping lowest for sensory range on account of this or, conversely, demoralized rank-and-file determined to be idling at a low ebb, rolling 3d6 and dropping the highest result can be appropriate.

A defender targetted by an effective distraction may mean a number of things, from temporarily shutting out their outer threshold of awareness as long as their attention lies elsewhere to allowing a Stealth attempt where none was possible before.

Surrounding environment

Circumstances propitious or adverse to the stealth attempt itself as related to matters of footing or background noise may be represented either through granting Advantage or Disadvantage to the stealth attempt, as usual. Though advantage could be modelled in terms of 5 point modifications to the DC rather than a second d20 roll, I’d personally disadvise this on the grounds of avoiding conflicting modifiers, as the DC is already being affected by the sensory thresholds.

Advantageous examples would include attempting stealth near the roaring banks of a waterfall, crossing a hall richly appointed with fur carpets or mingling amid a street alive with crowds whereas for disadvantageous examples one can imagine trying to sneak over creaky floorboards or forcing a path through patches of dried plant growth.

Some circumstances might simultaneously carry advantages (or the opposite) to both the stealth roll and the sensory distance, such as moving about unnoticed amid a foggy downpour, both impairing a sentry’s sensory range and granting advantage to the stealth attempt due to the muffled sound.

On Getting Caught (shades of failure)

Since stealth is acutely hinged on make-or-break, liable to result in a combat, a chase or on someone raising the alarm, it behooves careful approach by both referee and remaining players alike, firstly by attending to their fictional positioning as well as minding the sequencing of actions, as characters who “stay just outside the door, ready to spring if something goes wrong” might realize only too late that they’re actually three full combat rounds away from being of any use. In parallel to this a basic mechanical gradation of failure becomes important, as failing a Stealth check at a guard's farthest sensory tier cannot mean quite the same as it happening at a closer distance.

A simple failure will thus mean enough of a disturbance has been made to potentially give a character’s presence away. Yet this, depending on target and circumstance, won’t necessarily mean a character finds his outline starkly painted against a white background all of a sudden, rather it will mean a prey might instinctively flee, a predator or guard cautiously investigate (prompting an active Perception check against the rolled stealth total), and a social creature may hesitantly start seeking to get the word out. All cases where a decision isn’t immediately apparent should merit randomization in the shape of a Wisdom check or a reaction roll adjusted by a halved-Wisdom mod, with low numbers bringing ill to the character, middling totals granting a round of indecision to be followed by further rolling and the unlikely boxcars or natural one meaning the target ends up shrugging things off or talking himself out of alarm.

In any event, failure is still failure. The character who makes a sound is merely granted a chance to retreat or hide but may not reattempt an approach under Stealth and the alerted target, despite not necessarily pin-pointing an intruder, becomes agitated enough to be impossible to surprise. All of this, of course, is mooted in the face of a fumbled roll, which does pretty much equate to doing something egregious enough to be loudly and clearly found out.

Ultimately, uncertainty and indecision are ores that lie in rich, deep veins, ready to be mined by a canny referee for tension at the table, without it ever straying into fudging.