in this vein:
If yourre proficient in daggers and crossbows, could you utilize something like a crossbow bolt AS a dagger (1d4 piercing) in melee?

Its technically a part of a weapon youre proficient in, used like one youre also proficient in…

— BC Jesse (@Ghost_Hack) September 9, 2018

Want to use a crossbow bolt as a dagger? Check out the rules on improvised weapons in the "Player's Handbook" (p. 147) for how to use weapons in unusual ways. #DnD https://t.co/XJ1jnVoVQK

— Jeremy Crawford (@JeremyECrawford) October 3, 2018

@JeremyECrawford PHB 201 says: "A cantrip is a spell that CAN be cast […] without a spell slot".

Can you voluntarily spend a spell slot on a cantrip? (For instance, to protect it from Counterspell?)

Obviously, there would be no other benefits / damage bonuses.

Thank you! <3

— fek (@fekfekfekfek) October 10, 2018

A cantrip never uses a spell slot. #DnD https://t.co/RiI6gxWIto

— Jeremy Crawford (@JeremyECrawford) October 10, 2018

@JeremyECrawford If an Eldritch Knight uses a bonus action spell, are they limited to just one cantrip with a casting time of 1 action, or could they cast two if they burn their Action Surge? The wording on PHB 202 says you can cast "a cantrip" (singular) #sageadvice #DnD (1/2)

— DM's Workshop (@DMsWorkshop) August 3, 2018

Is there a limit on the number of spells you can cast on your turn? Take a look at the Sage Advice Compendium for the answer: https://t.co/nlIvbEC7D7 #DnD https://t.co/1DUE1ovffW

— Jeremy Crawford (@JeremyECrawford) August 3, 2018

Can I add Colossus Slayer damage on my regular turn and then again on my reaction? (ie comander’s strike, opp. attacks)

Colossus Slayer works once per turn. That usually means once on your turn and once with an opportunity attack on another turn. #DnD https://t.co/lW93vvHZ5i

— Jeremy Crawford (@JeremyECrawford) December 4, 2016

.@mikemearls, @JeremyECrawford – Please help!

A Ranger with Colossus Slayer: As a #DungeonMaster, I wasn’t sure if this could be used by the Ranger on both their own turn, and an attack of opp.

In 2016 you both #SageAdvice’d differently – is there a definitive answer?#DnD pic.twitter.com/XXwDKbu6AR

— Rob 🎲 🍷 🏳️‍🌈 (@DiceRefgemlin) October 9, 2018

My answer is the definitive one. Colossus Slayer doesn't say anything about the turn being your turn.

— Jeremy Crawford (@JeremyECrawford) October 11, 2018

@JeremyECrawford The PHB talks about how if the player's CON drops for some reason they lose HP for each modifier that goes down (if any), but I can't seem to find anything that says what happens if it drops to zero. Do they die like with STR/INT on the Shadow/Intellect Devourer?

— Rory Knox (@r0ryk) August 19, 2018

If an effect in D&D lowers an ability score, the text of that effect tells you if something especially dire happens if the score reaches 0. There's no general rule. #DnD https://t.co/DFHYhZmCbn

— Jeremy Crawford (@JeremyECrawford) August 19, 2018

@JeremyECrawford @ChrisPerkinsDnD Are the daggers produced by the “Bracers of Flying Daggers” (WDH p190) Thrown Melee Weapons or Ranged Weapons??? Unclear as text says “making a ranged attack with each dagger”
Asking for a Sharpshooter friend.

— Daniel C Eagle (@danielceagle) September 8, 2018

Daggers are melee weapons. Because they have the thrown property, they're not improvised weapons when used to make ranged attacks.

If a rule says you're making a ranged attack with a dagger, that rule doesn't change the fact that the dagger is a melee weapon. #DnD https://t.co/yzImWc9gS1

— Jeremy Crawford (@JeremyECrawford) September 9, 2018

So it's a ranged weapon attack with a melee weapon?

— Walrock Homebrew (@WalrockHomebrew) September 9, 2018

When you make a ranged attack with a weapon, you're making a ranged weapon attack. #DnD https://t.co/XapYj6R5z6

— Jeremy Crawford (@JeremyECrawford) September 9, 2018

Curious whether something is a melee weapon or a ranged weapon? Take a look at the Weapons table in the "Player's Handbook" (p. 149). The table organizes the weapons into melee and ranged categories. #DnD

— Jeremy Crawford (@JeremyECrawford) September 9, 2018

But a "ranged weapon attack" is not a "ranged weapon" for things like Sneak Attack, correct?

— Matthew Domville (@mattdomville) September 9, 2018

An attack is something you do.

A weapon is one of the things you can use to do it. #DnD https://t.co/xEhOEYCSRQ

— Jeremy Crawford (@JeremyECrawford) September 9, 2018

The older I get, the more I internalize this important lesson: very few things in life are obvious to everyone.

— Jeremy Crawford (@JeremyECrawford) September 9, 2018

@mikemearls Action Surge and spell casting. Two spells(not cantrips) in 1 round? Help us @mikemearls you're our only hope.

— Nerdarchy (@Nerdarchy) March 6, 2015

@CraigSchwarze You can use Action Surge to cast a second spell, provided that both spells take 1 action to cast. @mikemearls @Nerdarchy

— Jeremy Crawford (@JeremyECrawford) March 6, 2015

Quickened Spell does make it possible to cast two 1-action spells, by turning a 1-action spell into a bonus-action spell.

— Jeremy Crawford (@JeremyECrawford) September 26, 2018

Hello @JeremyECrawford please could you tell if in DnD 5th ed. is it possible cast find familiar to get a improved familiar, such as Pixie or an Imp? Thanks for help.

— Leandro (@androalmeida) September 6, 2018

The find familiar spell lists the forms that the familiar can assume. Pixie and imp aren't on that list. A warlock with Pact of the Chain gets a longer list.

If you'd like to bond with a pixie or an imp, you need to befriend the creature or somehow bind it to your service. #DnD https://t.co/0D7iavEzWO

— Jeremy Crawford (@JeremyECrawford) September 6, 2018

Thanks for reply, but please I have another question for you: What about variant rules described on Volo's Guide? See attached pic, please. Thanks in advance @JeremyECrawford ! #DnD pic.twitter.com/4tk7uRSiva

— Leandro (@androalmeida) September 6, 2018

A variant rule in D&D doesn't affect how something else works in the game unless your group adopts that variant. If you do adopt it, enjoy! #DnD https://t.co/tgBLZNH8H1

— Jeremy Crawford (@JeremyECrawford) September 6, 2018

Yes, that variant is one way a DM can handle familiars.

— Jeremy Crawford (@JeremyECrawford) September 6, 2018