are newer expansions (as Xanathar’s) always backward compatible with older adventures? (as Tyranny of Dragons?)Yes, that is the intent

— Mike Mearls (@mikemearls) November 26, 2017

Text trumps table

— Mike Mearls (@mikemearls) November 7, 2017

In your opinion, would it be balanced to give the Shadow Monk the spell “Shadow Blade” from Xanathar’s Guide to Everything for 4 or 6 ki?It should be – spells costed out in ki are basically spell slots. No books here, so exact cost is like 👻

— Mike Mearls (@mikemearls) December 3, 2017

How come the Arcane Archer gets access to more magic arrow types, but not more chances to use them each day? Was the other considered? Idea was to keep them powerful – flat uses, but power increases, mainly to keep magnitude of effect relevant/noticeable

— Mike Mearls (@mikemearls) December 4, 2017

DOWNLOAD
http://www.dmsguild.com/The-Lingering-Soul

Why can’t an Arcane Archer use crossbows? My concept for a sea elf Arcane Archer sort of needs it.Huh – no balance reason, really an oversight

— Mike Mearls (@mikemearls) December 3, 2017

If I create a Ranger using a XGtE subclass and the revised ranger UA, should I add the Extra Attack at 5th level? Yes.

— Jeremy Crawford (@JeremyECrawford) November 27, 2017

Arcane Archer now gets Magic Arrow at 7th instead of 3rd, but Arcane Shots still require a magic arrow. Is that intended, and if so is it expected that 3rd-level characters will obtain a supply of magic arrows? Mistake – strike the magic arrow reference from the 3rd level ability

— Mike Mearls (@mikemearls) November 12, 2017

If healing spirit has felt too effective in your game, try this house rule, which holds the spell to our expectations for it: the spell ends once the spirit has restored hit points a number of times equal to twice your spellcasting ability modifier (minimum of once). #DnD https://t.co/o5pnvl2fLd

— Jeremy Crawford (@JeremyECrawford) November 29, 2017

the “twice your spellcasting ability” refers to the number of times it heals or to the number of hit points healed? The number of times.

— Jeremy Crawford (@JeremyECrawford) November 29, 2017

I am quite certain that your proofreading squad is first-rate. That wasn’t a slam or a put-down.
It’s just that different brains notice different things. Zero defects is the goal, right? Indeed, which is why many people from different academic backgrounds review each of our manuscripts. Unfortunately, things sometimes slip through, and then we correct them.

— Jeremy Crawford (@JeremyECrawford) November 29, 2017

I'm going to keep the spell as is. If one spell "breaks" my game, I'm not DMing – I'm just passively adjudicating.

I think the spell is exactly what it needs to be, math or no math. I don't rely on my PCs lacking HP to challenge them. 💖💖💖

— Justin Ray Glosson (@ivstinus) November 29, 2017

We actually balance the game assuming player characters are at full health. We have to do that, since an encounter could happen at any point. An extra powerful healing spell doesn't unbalance the game. But it can disrupt what feels right to a group. That's what concerns us. #DnD https://t.co/W60qevhfUh

— Jeremy Crawford (@JeremyECrawford) November 29, 2017

I can understand that and thank you for your dedication, but my reply was more engineered at a negative comment posted by someone else – my apologies.

I love the theme of the spell, and while I can see major differences compared to “prayer of healing,” druid healing! Yay! 😉 Oh, I didn't think you were being negative. I was pointing out that your instincts are right about how the game is designed. 😀

— Jeremy Crawford (@JeremyECrawford) November 29, 2017

This seems like an odd decision given the common encounter structures that are used in nearly every game I’ve played; that is: minions & toughs, then a boss. The structure you’re referring to is adventure design, not combat design.

— Jeremy Crawford (@JeremyECrawford) November 30, 2017

Its a baffling concept, (was trained from 3.5, which was presented as a game of attrition) but I guess it makes sense. After a fight the players heal to full via hd anyway. The adventuring day is a mix of excitement and attrition. That’s not the same thing as designing combat systems.

— Jeremy Crawford (@JeremyECrawford) November 30, 2017

So if I give Acererak wish and have him use it to cast this spell at 8th level, how big of a jerk would I be as a DM? What about if he casts time stop first? I'd just be laughing that Acererak is wasting a wish on this spell.

— Jeremy Crawford (@JeremyECrawford) November 30, 2017

What is the point of all the resting mechanics that are part of the core game then if it seems the default assumption is full hit points for everyone? Certain tabletops work like that with a refresh between encounters, why did you not go that direction with 5e?

— Marc Sharma (@LeMarcSharma) November 30, 2017

The rest rules in D&D help create a certain narrative tempo and are part of our adventure/campaign design, not to be confused with combat design and the design of other subsystems. Tiring out is an important part of the adventuring narrative. #DnD https://t.co/JyLRKwDYss

— Jeremy Crawford (@JeremyECrawford) December 1, 2017