RAW QUESTIONS / FAQ / EVENT LOGISTICS
PURE RAW FORUM
Vision or "seeing" is a bedrock concept deeply entwined into the RAW. Unfortunately the actual passages of the RAW are scattered and fragmented. What follows is an attempt to consolidate, compare and inter-relate all of the rules relating to vision and other forms of "seeing."
Starting with a good rule summary here:
https://www.5esrd.com/gamemastering/hazards/darkness-obscurement/
Lightly Obscured (Dim Light) = disadvantage on perception
Heavily Obscured (Darkness) = Blinded condition
PHB: A heavily obscured area blocks vision entirely. A creature in a heavily obscured area effectively suffers from the blinded condition.
Furthermore, errata says:
Errata: A creature effectively suffers from the blinded condition (see appendix A) when trying to see something in that area.
https://twitter.com/JeremyECrawford/status/844028864191913985
https://www.sageadvice.eu/stealth-invisibility-and-blindsight/
NOTE ON THE INVISIBLE CONDITION:
In a 2021 Sage Advice podcast Q&A Jeremy Crawford fleshed out more details surrounding the interaction of the Invisible condition with different vision types, placing it into a special category based on the wording of the Invisible condition as an instance of "specific supersedes general." Unfortunately this does not seem to have been reflected in any written rulings nor in the Sage Advice Compendium, which remains the only official source of RAW rulings, though it seems this is intended to be official. Under the ruling the Invisible condition grants advantage/disadvantage independent of the capacity to "see" or the blinded condition, simply as a virtue of the condition itself, unless explicitly countered by other effects. In such cases it is possible to "see" an invisible creature (ie. with See Invisible spell or truesight), thus allowing spell effects that require "seeing" the target to target the creature (ie. Counterspell), but the Invisible condition will still convey the advantage/disadvantage benefits to attacks.
SUMMARY OF VISION & PROXY SENSES:
Regular Vision:
- No penalty through unobscured Bright Light.
- Disadvantage on Perception through Dim Light/Light Obscurement.
- Defeated (functionally Blinded condition, stealth possible) by any Darkness, Heavy Obscurement, Total Cover, Invisibility, illusions that block line of sight.
Darkvision:
- No penalty through unobscured Bright or Dim Light.
- Disadvantage on Perception through non-magical Darkness/Light Obscurement.
- Defeated (functionally Blinded condition, stealth possible) by magical Darkness, Heavy Obscurement, Total Cover, Invisibility, illusions that block line of sight.
Devil Sight:
- No penalty through unobscured Bright Light or normal and magical Darkness.
- Disadvantage on Perception through Dim Light/Light Obscurement.
- Defeated (functionally Blinded condition, stealth possible) by Heavy Obscurement, Total Cover, Invisibility, illusions that block line of sight.
Truesight:
- Can "see" through unobscured Bright Light, magical and normal Darkness, Invisibility, and illusions.
- Disadvantage on Perception through Dim Light/Light Obscurement.
- Defeated (functionally Blinded condition, stealth possible) by Heavy Obscurement, Total Cover.
Blindsight:
- Can "see" through Heavy or Light Obscurement, Bright or Dim Light, magical and normal Darkness, Invisibility.
- No disadvantage on Perception for anything.
- Defeated (functionally Blinded condition, stealth possible) by Total Cover.
- Open Question: illusions.
Tremorsense:
- (IFF in contact with same ground/surface) Can "see" through Heavy or Light Obscurement, Bright or Dim Light, magical and normal Darkness, Invisibility and all degrees of Cover.
- No disadvantage on Perception for anything.
- Defeated by flying, incorporeal, successful Stealth vs. Perception.
- Open Question: illusions, what conditions permit stealth?
So flipping it around:
1. A creature in normal darkness would be seen by darkvision, devil sight, truesight, blindsight and tremorsense (IFF) but would be Unseen from those using regular vision.
2. A creature in magical darkness would be seen by devil sight, truesight, blindsight and tremorsense (IFF) but would be Unseen from those using regular vision or darkvision.
3. An invisible creature would be seen by truesight, blindsight and tremorsense (IFF) but would be Unseen from those using regular vision, darkvision or devil sight.
4. A creature in dense fog (heavy obscurement) would be seen by blindsight and tremorsense (IFF) but would be Unseen from those using regular vision, darkvision devil sight or truesight.
5. A creature behind Total Cover would be seen by tremorsense if in contact with same ground/surface and not successfully in stealth but would be Unseen from those using regular vision, darkvision, devil sight, truesight or blindsight.
6. A creature flying behind Total Cover would be Unseen by everything.
I like this. Many of the live plays I've seen have a house rule that darkvision is flawless in darkness, rather than still causing disadvantage on perception checks. Or maybe it isn't a house rule and they just forget? Unless they have a human or halfling along they just ignore non-magical darkness.
I think most players and DMs alike generally do not realize that perception has disadvantage in dim light, or they forget about it in the heat of play. It's a critical rule to use though, or else you end up nerfing rogues and any other creature that relies on stealth.
