How does the warlock's Devil's Sight eldritch invocation work?

Question

The Warlock Invocation Devil's Sight (PHB p108) is described like this:

You can see normally in darkness, both magical and nonmagical, to a distance of 120 feet.

How should this be interpreted, given the undefined use of the word "normally" and the description of a real devil's Devil's Sight ability?

Barbed Devil (MM p.70):

Magical darkness doesn't impede the devil's darkvision

Answer 1

The Text is Clear

The Devil's Sight invocation reads simply:

You can see normally in darkness, both magical and nonmagical, to a distance of 120 feet.

Dim light is not mentioned, but is mentioned in every other form of Deprovision given to player features. This omission means that there is no benefit from the invocation until you get into actual darkness.

So, what "normally" means is that you can see if there were light; in full color, with no disadvantage imposed to attacks or sight based skill checks for reasons of darkness.

The Monster Manual definition of Devil Sight is specific to monsters with it, and don't apply to Warlocks, it doesn't change or affect how the invocation works.

Designer's Intent

Jeremy Crawford answered a question like this on Twitter in November 2015. while his tweets were still considered official rulings. Jeremy Crawford confirmed that Devil's Sight us meant to kick in only in total darkness. When asked:

Devil's Sight invocation gives you no benefit in dim light and full color vision in darkness. Intended?

He responded:

Devil's Sight is meant to be an eerie ability: "Douse that candle so that the Dark Powers will lend me sight."

It is the designers intent that Devil's sight allows you to see in total darkness as if it were full light, but gain no bonuses in dim light. Other sources of darkvision would still apply.

Answer 2

Devil's Sight (PHB p108):

You can see normally in darkness, both magical and nonmagical, to a distance of 120 feet.

I always assumed it meant you could see as if it were "normal" lighting conditions up until I tried to answer this question and threw up a second interpretation I'd not considered before.

Interpretation 1

- you see in darkness, magic and mundane, as if it were normal lighting conditions for a normally sighted person

This interpretation makes it a super-darkvision ability, where you see though darkness of any kind as if it was bright light, and in colour.

Interpretation 2

An actual devil's Devil's Sight ability is described like this (for instance the Barbed Devil MM p.70):

Magical darkness doesn't impede the devil's darkvision

The devil's darkvision is listed as a sense separately from the Devil's Sight ability.

Using this as the basis for interpreting the Warlock invocation puts the Warlock and the devil's abilities in line:

- you see normally for you in darkness, both magical and nonmagical

Which interpretation is right?

Pro interpretation 1:

• a simple rule: the warlock can see in the dark, magic or not
• no other supporting description: if darkvision is required to use the ability effectively, you would expect this to be detailed in the invocation description, for clarity if nothing else
• darkvision is not on the warlock spell list, which you would expect if this invocation required it to be useful
• Sage advice on Devil's Sight supports this interpretation by accepting the premise of the question, though it reads like a bit of a quip

Con interpretation 1:

• "Normal" is completely undefined in these terms, i.e. what is "normal"? Full daylight, bright light, does it allow use of Eyes of Minute Seeing etc.?
• The description does not mention dim light at all, so RAW the warlock's sight (if no darkvision) gets steadily worse as the light level lowers until it becomes darkness, at which point it suddenly is as good as ever which is ugly at the very least

Pro interpretation 2:

• a simple rule: magical darkness does not effect your darkvision, it plays really easily with little complexity at all
• The term "normal" makes sense: it means "as the Warlock would normally see right now if it weren't dark"
• No issue with what happens as the light level gets worse, you either have darkvision or you don't
• It is effectively the same ability as an actual devil's Devil's Sight

Con interpretation 2:

• darkvision is not on the warlock spell list, which you would expect if this invocation required it to be useful
  • Sage advice on Devil's Sight suggests interpretation 1 by accepting the premise of the question, though it reads like a bit of a quip

This list of pros and cons actually suggests to me that in fact interpretation 2 is the correct one: The Warlock is effectively given the Devil's Sight ability that devils have and it provides no inherent darkvision capability at all.

The only cons to this that I can see are a throwaway quip in response to a tweeted question on Sage Advice and the fact darkvision isn't on the spell list, where as interpretation 1 has real flaws and edge cases that don't make sense.

On reflection, while core rulebook RAW support either interpretation and interpretation makes more sense, Jeremy Crawford's sage advice clearly shows interpretation 1 is the intent of the game designer and should be the one taken.

Answer 3

According to Jeremy Crawford's tweet, a follow-up comment in that Twitter thread and the other quotes linked to above, you'd run into the following type of situation. (JC's tweets, historical and continuing, are no longer canon as of 2019 as remarked in the comments.)

A warlock character with racial darkvision out to 60' - common among game races for characters - who has the Devil's Sight invocation, is in an area of dim light extending out to 120' or more. Someone has cast Darkness 15' radius on a spot 105' from the warlock character. So the warlock can see as though in bright light out to 60', then beyond all is dark, except for a 30' diameter region starting at 90' in one particular direction, where it's like bright light. So in normal human terms, the warlock's vision of the Darkness area is not like seeing the circle of light from a campfire in the near distance, when the woods around you are dark - more like someone lit a flare over that area, but there's a zone he can't see at all before it.

Anyway that's kind of weird and hard to keep track of. As Jeremy Crawford has written many places, adapt the rules to fit your game. In our campaign, a warlock's Devil's Sight is like Darkvision 120' - which gives bright light vision in dim light - with the added benefit that the warlock also has bright light vision in darkness, magical and non-magical, out to that distance. It's not a big advantage on the original, doesn't make the invocation hugely overpowered, and is much easier to keep track of in the game.

Answer 4

This is Jeremy Crawford's official statement:

If you have Devil's Sight, darkness within 120 feet of you effectively isn't there. For purposes of sight, you can treat that area as if it's brightly lit.