D&D 5E Invisibility, non-instantaneous spells, and spell effects

[Plaguescarred]

Ready Action with spell is not acting like Counterspell.
While both are reaction, which you may take when you see a creature casting a spell, only Counterspell specifically can interrupt a creature in the process of casting a spell, Ready Action follows the general rules on reaction timing.

 

[Lyxen]

-I ready to cast magic missile when they cast a spell
-Your readied action goes off directly AFTER the triggering action occurs
-They cast Alarm...as a ritual
-10 minutes later: you cast magic missile

It does not work that way, your readied action (and the spell energy) expires at the start of your next turn: "...which lets you act using your reaction before the start of your next turn."

This is why you declare after he "starts casting", whether this takes zero time (because there is always a beginning), or an instant, it will still be before the spell is completed.

 

[TaranTheWanderer]

It does not work that way, your readied action (and the spell energy) expires at the start of your next turn: "...which lets you act using your reaction before the start of your next turn."

This is why you declare after he "starts casting", whether this takes zero time (because there is always a beginning), or an instant, it will still be before the spell is completed.

I was trying to be funny. I should have added a sarcasm emoji

 

[Lyxen]

I was trying to be funny. I should have added a sarcasm emoji

I was suspecting something of the kind, and indeed emojis help, but in any case it's a common misconception about readying actions, so I don't think it was lost.

 

[James Gasik]

Curiously, something that I ran into that hasn't come up yet (so I haven't needed to point this out) is that if you set a trigger for a reaction, you don't have to make it at that time. In fact, if the trigger happens more than once in a turn, you can make the reaction in response to any of these triggers should you choose.

 

[Irlo]

I agree with the reasoning, although honestly, if I was casting MM, I would cast it when he starts casting, whatever he is casting, or I would prepare an AoE if he turned invisible, the combination of MM + Becomes invisible is strange to me.

I chose that particular example only to bring into question whether the onset of a non-instantaneous spell is itself interruptible or not following completion of casting.

I've never seen a player try this in a game and I never will.

 

[Lyxen]

Curiously, something that I ran into that hasn't come up yet (so I haven't needed to point this out) is that if you set a trigger for a reaction, you don't have to make it at that time. In fact, if the trigger happens more than once in a turn, you can make the reaction in response to any of these triggers should you choose.

Hmmmm. While I see your point, the wording is again only partially precise: "When the trigger occurs, you can either take your reaction right after the trigger finishes or ignore the trigger."

Note that it is "the trigger" every time, which could be taken to mean that it's specific and there is only one possible. After that, I suspect that it depends on the wording of the trigger, but I tend to use fairly specific ones, not things like "if anyone starts to cast a spell...", it's more "if that specific guy starts to cast a spell" to avoid this kind of ambiguity.

 

[James Gasik]

I mean, it was one of you know who's tweets, that I ran into while researching a different topic. So take it with a grain of salt, but apparently he believes that if your trigger is an event that can happen more than once in a turn, you can choose to react to any one of those triggers if you want.

 

[Dausuul]

Under the Ready action, there are examples that break up what a target is doing, such as "If the cultist steps on the trapdoor, I'll pull the level that opens it". As such it seems that the only limit to the trigger is "perceivable circumstance", there is no explicit or implied limitation that it can not interrupt part of an action. And the trigger occurs after the perceivable experience completes, not the whole action completes. It happen when they step on the trapdoor, not when they have completed a move that takes them off the trapdoor.

That's not an action being interrupted. "Stepping on the trapdoor" is movement, which I already covered. (So is "if the goblin moves up next to me," which is the other example offered.)

We know from the Identifying a Spell section of Xanathar's that a reaction can be used to identify a spell explicitly before it is cast. So there is a period after casting is started before the casting is finished that can accommodate a Reaction during that period.

Obviously it is possible for a reaction to interrupt a spell, or counterspell wouldn't work. But we are not talking about any random reaction; we're talking about the reaction granted by the Ready action, which specifically takes place after the trigger.

Now, to be clear: My ruling on actions being uninterruptible* is not the only possible interpretation of RAW. But it is a valid interpretation of RAW, not contradicted by anything in the books that I can see, and it heads off a lot of weird timing questions.

*With the exception of actions, such as Attack with multiple attacks, that allow the person acting to do other things in the middle; and movement, which is not an action at all. I may start putting this as a footnote in every single post I make in this thread.

 

[James Gasik]

That's not an action being interrupted. "Stepping on the trapdoor" is movement, which I already covered. (So is "if the goblin moves up next to me," which is the other example offered.)


Obviously it is possible for a reaction to interrupt a spell, or counterspell wouldn't work. But we are not talking about any random reaction; we're talking about the reaction granted by the Ready action, which specifically takes place after the trigger.

Now, to be clear: My ruling on actions being uninterruptible* is not the only possible interpretation of RAW. But it is a valid interpretation of RAW, not contradicted by anything in the books that I can see, and it heads off a lot of weird timing questions.

*With the exception of actions, such as Attack with multiple attacks, that allow the person acting to do other things in the middle; and movement, which is not an action at all. I may start putting this as a footnote in every single post I make in this thread.

And this is really the crux of the issue. You are very likely correct that actions cannot be interrupted. But the rules don't say that. They should say that. They could have said that. But that's not what they say. So we have to draw a line from "react to a trigger that is not an action, but a perceivable event" and "reactions cannot interrupt their trigger" to "reactions cannot interrupt an action" that there's no reason to do, since it would be trivial for the rules to say that.

There's only a few possibilities here as a result:

1) somehow, the developers thought everyone would think this way and assume this is the way the rules work on their own.

2) it's just terrible wording.

3) the developers left the door open so that either ruling (readied actions can interrupt actions vs. readied actions can interrupt actions) was perfectly valid and left to the individual groups to decide upon.