Recooked: Senses, Hiding, and Cover
This is Recooked: Senses, Hiding, and Cover v3 by Recatek. For the latest version, check GMBinder.
Like some, I find the rules for fundamental senses to be contradictory or unclear in the core D&D material. If you struggle with this as well, then this supplement is for you. These rewritten rules are intended as a drop-in replacement to clarify any vague language, gather everything in one place, better adjudicate odd interactions, and close some infamous loopholes in the original rules text.
For the most part, these revised rules are backwards compatible with spells, monster stat blocks, magic items, abilities, and so on using these new keyword definitions. The goal of this supplement is to more clearly define the rules and mechanics of senses, so that players and DMs alike can add better gameplay building blocks to their encounters, with more intuitive ramifications and fewer table rulings.
Rules Replacement
Unless otherwise stated, any keyword, condition, or term defined here overrides and replaces that from the fifth edition rules. Terms like heavily obscured and half cover will be fully redefined in this supplement. Spells and effects that reference these terms should use this supplement's definitions, rather than those of the original rulebooks.
Making Sense of Senses
In the real world, we use a number of senses to perceive what's around us, but for the sake of these rules, we will usually focus on just three: sight, hearing, and smell. These senses are a necessary part of perception, and many spells and abilities interact with or require one of these three senses as part of their execution.
Relying on Senses
When making a Wisdom (Perception) or other related ability check—active or passive—your DM will determine which senses you rely on for that roll. Certain conditions or abilities can affect the roll, depending on which senses you rely on at the time. Spotting a desert oasis on the horizon may rely on sight alone, while noticing the signs of an impending ambush may rely on sight, hearing, and even smell. When you rely on one or more senses, it affects the ability check in the following ways:
- If you lack one or more of the senses that an ability check relies on, your DM may impose disadvantage on the roll.
- If you lack all of the senses that an ability check relies on, the roll automatically fails.
Sight in Combat
Sight is an especially important sense for aiming attacks in combat. If you can't see an opponent, then attack rolls you make against that opponent have disadvantage and that opponent has advantage on attack rolls it makes against you.
Special Senses
Some creatures have sensory abilities that allow them to perceive the world around them in special ways.
Darkvision
Many creatures in the worlds of D&D, especially those that dwell underground, have darkvision. Within a specified range, a creature with darkvision can see in dim light as if it were bright light and in darkness as if it were dim light, so areas of darkness are only lightly obscured as far as that creature is concerned. However, the creature can't discern color in darkness, only shades of gray.
Blindsight
Creatures without eyes, such as oozes, and creatures with echolocation or heightened senses, such as bats and true dragons, have blindsight. A creature with blindsight can, out to a specified range, see normally in dim light and darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, see creatures and objects that are heavily obscured or lightly obscured with no penalty, and ignore the blinded condition. These abilities come with one exception: a creature or object can't be seen using blindsight if it has total cover from the observer—solid obstacles still obscure this sense whether they are opaque or transparent.
Truesight
Powerful fiends, celestials, and other immortal creatures have truesight. A creature with truesight can, out to a specified range, see normally in dim light and darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, perceive the original form of a shapechanger or a creature that is transformed by magic, and see into the Ethereal Plane. Truesight is unavailable if the creature cannot see.
Tremorsense
Many burrowing creatures, such as ankhegs and umber hulks, have this unique sense. A creature with tremorsense can, out to a specific range, detect and pinpoint the origin of vibrations, provided that the creature and the source of the vibrations are in contact with the same ground or substance. This can be used to locate, but not see, the creature or object causing the vibration. Tremorsense can't be used to locate airborne or incorporeal creatures. Solid obstacles do not obscure this sense.
Tremorsense, not Tremorsight
Tremorsense is an independent sense. It allows a creature to pinpoint vibrations and contest Dexterity (Stealth) checks to hide by moving or especially disruptive creatures, but it is not a form or replacement of sight, hearing, or smell. Many monsters with tremorsense can still see, while some others may have blindsight to compensate.
Vision and Light
The most fundamental tasks of adventuring—noticing danger, finding hidden objects, hitting an enemy in combat, and targeting a spell, to name just a few—rely heavily on a character’s ability to see. Darkness and other effects that obscure vision can prove a significant hindrance.
Obscured Areas
Visible phenomena can make it difficult to perceive objects or creatures by hiding them from view. These situations can occur naturally, or be created by spells or effects.
A lightly obscured area, such as dim light, patchy fog, or moderate foliage, makes it difficult, but not impossible, to see inside. Creatures have disadvantage on Wisdom (Perception) checks that rely on sight when trying to see into that area, unless your DM decides their other senses can compensate.
A heavily obscured area—such as darkness, opaque fog, or dense foliage—blocks sight entirely. A creature effectively suffers from the blinded condition when trying to see into that area. A heavily obscured area is also lightly obscured.
Some effects may obscure vision outside of their area alone. Fog, foliage, swarms, and other phenomena can obscure not only their immediate area, but also the area behind them relative to a viewer.
Illusions and Obscurement
Some spells—such as Minor Illusion and Silent Image—can create visual effects that block sight with an opaque image. For as long as a creature can't see through the illusion's visual effect, the area behind it from that creature's point of view is considered heavily obscured to that creature. For Truesight and other special senses, a spell's visual effect is considered an illusion only if it is from the Illusion school.
Obscuring other senses
As a DM, you may decide to obscure other senses in an area. A loud storm or waterfall may cause all nearby creatures to effectively suffer from the deafened condition, while traveling through foul sewers may impose the anosmic condition. Yuck!
Levels of Light
The presence or absence of light in an environment by nature or magic means creates three categories of illumination.
Bright light lets most creatures see clearly. Even overcast days provide bright light, as do torches, lanterns, fires, and other sources of illumination within a specific radius. You are also in direct sunlight if you are in bright light from the sun or from some magical effect that creates sunlight by name.
Dim light creates a lightly obscured area. An area of dim light is usually a boundary between a source of bright light, such as a torch, and surrounding darkness. The soft light of twilight and dawn, or a particularly brilliant full moon might also bathe the land in dim light.
Darkness creates a heavily obscured area. Characters face darkness outdoors at night (even most moonlit nights), or within the halls of an unlit dungeon or a subterranean vault.
Magical Darkness
Some magical sources of darkness can follow special rules. For example, the Darkness spell prevents nonmagical light from illuminating it, and darkvision from seeing through it. Here blindsight, truesight, and some other abilities can see normally, because the spell doesn't prevent them from doing so. By comparison, other sources of darkness like the Hallow spell have no rules against darkvision. No single rule covers every magical darkness effect. Be sure to read an effect's description to learn who can and can't see inside, as spell effects do only what they say they do. For help in determining if an effect is magical, refer to the Sage Advice Compendium.
An effect creates bright light, dim light, or darkness only if it says so by name. For example, the first effect of Shadow of Moil heavily obscures you with "flame-like shadows"—not darkness. If you are heavily obscured by this effect, you can't be seen with darkvision or truesight because they don't apply to "flame-like shadows". Similarly, magical voids and spheres of blackness are not explicitly named levels of light.
Conditions, Revisited
These replace those from the Player's Handbook (PH 290). Conditions can apply automatically—for example, a blind creature should be treated as having the blinded condition.
Blinded
- A blinded creature can't see.
- The creature can't rely on sight for any ability check.
Deafened
- A deafened creature can't hear.
- The creature can't rely on hearing for any ability check.
Anosmic
- An anosmic creature can't smell.
- The creature can't rely on smell for any ability check.
Invisible
- An invisible creature or object is heavily obscured to any viewer without the aid of magic or special senses to see it.
Hiding
Hiding allows you to conceal your location from other creatures, even if they are aware of your presence. If you are not hiding, all creatures can pinpoint your location as long as they can detect you with at least one applicable sense, no check necessary. When you try to hide, make a Dexterity (Stealth) check. Until you are discovered or you stop hiding, that check's total is contested by the Wisdom (Perception) check of any creature that actively attempts to detect you. If a creature fails to detect you, that creature does not know your location and may be unaware of your presence entirely.
Most creatures stay vigilant and are able to see signs of danger all around them, unless circumstances limit their vision to a single direction or cone. You can't hide and are no longer hidden from a creature as soon as it can see you. Normally, that means a creature must be effectively blinded to you in order to hide and remain hidden from it. Under certain circumstances, your DM might allow you to stay hidden as you approach a creature that is distracted.
Where can you hide?
One way to hide from a creature is to be heavily obscured from it, making unable to see you. This can be done with darkness, total cover, invisibility, illusions, fog, and other environmental or magical phenomena. Special abilities like the Skulker feat can also allow you to try to hide and remain hidden even if you are only lightly obscured. If so, you are considered heavily obscured for the sake of hiding.
Detection with Senses
The senses a creature typically relies on to to detect you depends on whether you are stationary or moving.
Stationary. You can choose to make no sound or vibrations when attempting to hide without moving, so any attempt to detect you relies on sight alone. This usually means you are hidden so long as you are not seen, no check necessary.
Moving. You make soft sounds and vibrations when attempting to move while hidden, so any attempt to detect you relies on sight, hearing, or tremorsense if available.
Under certain circumstances, a creature might rely on smell or other senses to detect you, stationary or moving. The creature may be very close to you, or could have keen senses.
Passive Perception
When you hide, there's a chance someone will notice you even if they aren't searching. To determine whether such a creature notices you, your DM compares your Dexterity (Stealth) check with that creature's passive Wisdom (Perception) score, which equals 10 + the creature's Wisdom modifier, as well as proficiency (if applicable) and any other bonuses or penalties. When using passive perception, a creature must still rely on whatever senses are relevant to the current situation, just as if it were an active ability check, and receives advantage or disadvantage as normal. If the creature has advantage, add 5. For disadvantage, subtract 5.
Giving Away your Location
If you make a loud noise—such as shouting a warning or knocking over a vase—you give away your position and are no longer hidden. Falling, jumping, and other vibrations can also give away your location to creatures with tremorsense. Similarly, whenever you make an attack, you give away your location to your target when the attack hits or misses.
Casting a spell with a verbal component can also reveal your location. Your DM may require you to make an additional Dexterity (Stealth) ability check to cast a spell quietly enough to avoid detection by a creature that can rely on hearing nearby.
If a creature detects you, it may point out your location to others nearby, revealing your location to them as well.
Making Use of Cover
Walls, trees, creatures, and other obstacles can provide cover during combat, making a target more difficult to see, detect, or harm. A target can benefit from cover only when an attack or other effect originates on the opposite side of the cover. Going prone may also improve the effectiveness of cover.
Only solid objects can provide cover. Illusions, visual effects, and incorporeal creatures or objects can't be used as cover, though they may contribute to obscurement if they make a target more difficult to see.
Degrees of Cover
There are three degrees of cover. If a target is behind multiple sources of cover relative to an attacker, only the most protective degree of cover applies.
A target with half cover has a +2 bonus to AC and Dexterity saving throws. A target has half cover if an obstacle blocks at least half of its body. The obstacle might be a low wall, a large piece of furniture, a narrow tree trunk, or a creature, whether that creature is an enemy or a friend.
A target with three-quarters cover has a +5 bonus to AC and Dexterity saving throws. A target has three-quarters cover if about three-quarters of it is covered by an obstacle. The obstacle might be a portcullis, an arrow slit, or a thick tree trunk. A target with three-quarters cover is also lightly obscured.
A target with total cover can't be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely occluded by an obstacle. A target with total cover is also heavily obscured. In most cases, total cover is symmetrical—unless the target leaves that cover, you have total cover from it just the same as it has total cover from you. To attack a target from behind total cover, you must first leave that cover using your movement or some other means.
The Dungeon Master's Guide (DMG 251) provides helpful rules for determining a creature's degree of cover and lines of sight when using a grid or hex tilemap for combat.