@JeremyECrawford If someone has light cast on a portion of their clothing, and then they go invisible, would the light still be visible, potentially negating the disadvantage on attack rolls? #SageAdvice

— Hans Engvall (@hzedm) November 8, 2017

If the d20 roll for an attack is a 20, the attack hits regardless of any modifiers or the target’s AC. This is called a critical hit. I thought critical hit is in addition to the former effect, but apparently you changed it.You change it from"in addition, the attack is a critical hit" to " it is called a critical hit". Does that mean critical hit always ignore modifiers and target AC now?

— Mopo (@MGreat321) November 23, 2017

Rolling a 20 for an attack produces a critical hit. The section "Critical Hits" (PH, 196) then explains what happens when you score such a hit. #DnD https://t.co/n1srMuoNHT

— Jeremy Crawford (@JeremyECrawford) November 23, 2017

Adamantine Armor negates critical hits. The crux of the question is, does a natural 20 automatically hit as a result of being a natural 20, or does it automatically hit as a result of being a critical hit. Previous editions were clearer on this point."If the d20 roll for an attack is a 20, the attack hits regardless of any modifiers or the target's AC" (PH, 194).

— Jeremy Crawford (@JeremyECrawford) November 23, 2017

I know N20 is a critical hit and how the critical hit works when you roll damage. But ignoring modifiers and target AC are not tie to the critical hit in the original PHB, now srd and dndbeyond seem to imply that they do. In every version of the PH, rolling a 20 is what causes you to automatically hit.

— Jeremy Crawford (@JeremyECrawford) November 23, 2017

But the new print call this "phenomenon" (20 from d20) a Critical Hit (before was a separated thing). So Adamantine Armor would make you immune to this phenomenon (the auto-hit part of the critical hit)? Or only the double dice damage part? https://t.co/HtZyk8wJgz

— Matheus Ferreira (@MtS_Designer) November 23, 2017

Adamantine armor makes you immune to the effects of a critical hit—rolling the damage dice twice. In other words, the armor turns the crit into a regular hit. #DnD https://t.co/kyKLl9NlWe

— Jeremy Crawford (@JeremyECrawford) November 23, 2017

Would it also nullify other effects of a crit, like the beheaded by a Vorpal Blade?

— Francklin Oliveira (@Asmodha) November 23, 2017

A vorpal sword doesn't rely on you scoring a critical hit. It relies on you rolling a 20. Adamantine armor doesn't change the number on the d20. #DnD https://t.co/6MTP3Ev6sS

— Jeremy Crawford (@JeremyECrawford) November 23, 2017

So to conclude: A champion fighter roll a 19 against a creature with 20 AC wearing an adamantine armor. The fighter will still auto-hit that target even if this phenomenon of auto-hitting is called a critical hit (which the armor gives immunity). Yes, that fact hasn't changed since the core books were published.

— Jeremy Crawford (@JeremyECrawford) November 23, 2017

New Print read like this: N20=ignore modifiers and AC= Critical hit(also 2xdamage). Where as original read like N20=ignore modifiers and AC+Critical hit。
The new print seem to imply crit=ignore modifiers and AC and roll 2xdamage. Where as old crit=2xdamage. As the person who wrote both versions of that rule, I can tell you that the rule means what it says: rolling a 20 is what ignores AC. The 20 is also called a critical hit, the effect of which is explained in the critical hit rule.

— Jeremy Crawford (@JeremyECrawford) November 23, 2017

@JeremyECrawford do daggers count as swords for the sake of “any sword” magic items?

— Big Mike (@gooselord98) October 21, 2017

Daggers in D&D aren't swords. #DnD https://t.co/1AKLCXGi2I

— Jeremy Crawford (@JeremyECrawford) October 21, 2017

And rapiers?

— Caio (@caiowng) October 21, 2017

A rapier is a sword. #DnD https://t.co/53tZdRPGTk

— Jeremy Crawford (@JeremyECrawford) October 21, 2017

I feel like some of these could have just been googled The dictionary is also a useful resource.

— Jeremy Crawford (@JeremyECrawford) October 22, 2017

Jeremy, I’m surprised you’re not just pointing people to the dictionary on this one. 😉 @MerriamWebster says dagger=knife, rapier=sword. https://t.co/Il9F50VSqU

— James Wyatt (@aquelajames) October 22, 2017

Oh, I know. 😉

— Jeremy Crawford (@JeremyECrawford) October 22, 2017

Related question: Devil's Sight in Darkness spell. Does the 120' range limit how far you can see beyond the spell's area?

— Dan Dillon (@Dan_Dillon_1) October 18, 2017

The range of Devil’s Sight determines how much darkness the feature sees through. #DnD https://t.co/qst88uCFrv

— Jeremy Crawford (@JeremyECrawford) October 18, 2017

@JeremyECrawford thought scrolls couldn’t be cantrips? pic.twitter.com/Vj6RuVm59w

— Alvin Ty Law (@alvintylaw) October 12, 2017

Take a look at the spell scroll in the Dungeon Master's Guide (p. 200).

— Jeremy Crawford (@JeremyECrawford) October 12, 2017

@JeremyECrawford Does crouching (such as behind cover) count as being prone? Does it take extra movement to stand up from crouching?

— PJ Elliott (@Dachimotsu) November 18, 2017

There are no rules for crouching. #DnD https://t.co/reWfCt590x

— Jeremy Crawford (@JeremyECrawford) November 18, 2017

@JeremyECrawford Is Freedom of Movement Broken? It doesn't seem to help a Grappled or Restrained creature, at all. It this a mistake or working as intended? if your speed is 0, how do you expend 5 feet of movement?

— Keith (@Glytched) November 20, 2017

Freedom of movement is an example of a feature (an exception) that lets you circumvent a general rule; it lets you spend 5 feet of movement to escape a grapple, even though your speed is 0. Magic! #DnD https://t.co/KuvdyrLXPI

— Jeremy Crawford (@JeremyECrawford) November 20, 2017

So under freedom of movement, a creatures speed can be reduced to 0 (non-magically) but they are able to suspend 5ft to escape? So after that, (if in init.) their speed would still be zero for that turn?If you escaped the grapple, your speed isn’t 0 any longer.

— Jeremy Crawford (@JeremyECrawford) November 20, 2017