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

[Lyxen]

And the reaction happens after that circumstance "finishes." When does "starts to cast a spell" finish? When have you finished starting?

As soon as you have started, by definition, any time after the start, is not "the start"...

As far as I'm concerned, the answer is, "When you finish the spell."

Because the start of anything only finishes when the whole thing finishes ? What's the point of calling it "the start" then ? Honestly, that argument has no ground in actual use of the word "start".

Clearly I do indeed have to put this in every single post:
I rule that a readied action cannot interrupt other actions, except for 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.

You don't have to, since the above sentence in general is not a rules in the books, by any stretch of the imagination. Once more, the rules only do what they say they do. When something cannot be interrupted (for example, a dispel magic cannot interrupt an instantaneous spell), it is written in plain letters.

Do you have an example that involves the Ready action? Because the Ready action is the one that says the reaction takes place after the trigger finishes. If your examples are stuff like counterspell or the Xanathar's "identify a spell" reaction, they have nothing to do with this.

Do you have any example of something that cannot be interrupted ? Even the dispel magic above is borderline, the intent is not to interrupt, but it's what can be affected.

No one is disputing that reactions exist which can interrupt other actions. The question is whether Ready is one of them--and, in particular, whether the rules require Ready to be one of them.

And again, since the rules make no provision and ready actions are meant to interrupt someone's turn anyway...

 

[Irlo]

Otherwise might as well just use trigger "when a creature blink eyes" to just be allowed to react anytime you want and interrupt whatever is happening!

"Okay, everyone. Be ready to move 30' to the left as soon as Gimli blinks!"

 

[Plaguescarred]

Ive seen people trying it when blinking eyes, dropping held item such as pebble and other self-made events loll

It Will depend if the DM take event to refer to what is happening or if the start of it is sufficient to be an event in itself.

 

[Lyxen]

Ive seen people trying it when blinking eyes, dropping held item such as pebble and other self-made events loll

I have indeed seen many self-made events, in particular in order to coordinate an attack (I will attack after Darion attacks and I will target the sema creature unless it's already down), and I actually find this quite normal, for me it beats metagaming character-telepathy any day of the week...

It Will depend if the DM take event to refer to what is happening or if the start of it is sufficient to be an event in itself.

Exactly, and on this, in 5e, the DM is (properly) the right authority to tell what is possible or not.

 

[jgsugden]

Seeing as your [perceivable circumstance trigger] is [him turning invisible] and you cant target an invisible creature with magic missile, the answer is no.

If your [perceivable circumstance trigger] was something other than 'when he turns invisible' we could talk.

This has been addressed throughout, but there is no set explicit determination that invisibiloty is instantaneous rather than a fading out. When a player says, "when they turn invisible", I am not going to, as a DM, assume that they mean that in the most literal and definitive way, but are instead attempting to convey a concept, and as a DM I have a duty to help them figure out how to address that concept within the scope of the rules as I, as a DM, run them.

We're telling a good story. When the minutia of a rule makes for bad storytelling, and there is a way to work around it, you do a disservice to the group by not seeking ways to make it work better.

 

[NotAYakk]

The player describes what they'd like to do.

"If I see them start to fade away, I cast magic missile."

I guess this is because they have the drop on the target, but don't want to kill them if they surrender? Whatever.

Now, I'd adjudicate what happens. And what happens is going to be unreliable. Depending on the situation, they might get their magic missile off before the spell does, they might force a concentration check or not, they might have their magic missile fizzle. It might be decided based on fiat, or based on an ability check, or a contested check, or maybe random chance.

If I find that players are constantly doing contrived ready actions for whatever reason, I'll reconsider how it works. But the fact that it wasn't reliable to start with is key here. You are A against B.

Now, quite often, if the thing you are trying to react to is just as fast as the thing you are reacting with, the thing you are reacting to is more likely to finish before you get to finish yours.

 

[Blue]

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.

That last little bit shows the problem. The Attack action does not allow you to do other things in the middle of it at all. Movement, and movement only, has an exception listed in the movement section. There is no general exception for the Attack action, and anything that applies to it applies to everything else.

And it is perfectly acceptable to have triggers like "when attacked" or "when hit" that break up the Attack action. We know for a fact that Actions may be broken up mid-action with reactions like Battlemaster Riposte, Shield, etc. Therefore the idea that actions are uninterruptible by reactions is not a valid interpretation of the rules.

The Ready action, which the only rules limitations put on it are an "perceivable trigger", can in fact break up actions just like any other Reaction can, depending on the trigger.

 

[Rabulias]

The Attack action does not allow you to do other things in the middle of it at all. Movement, and movement only, has an exception listed in the movement section. There is no general exception for the Attack action, and anything that applies to it applies to everything else.

I do not think this true. A 6th level Bladesinger with two attacks could make one attack on an opponent (but not drop them), move away from them (provoking an Opportunity Attack), use their Reaction to cast shield against that OA, drop their current weapon, use their Use an Object to draw another weapon, use their Bonus Action to activate Bladesong (PHB p.180 under Bonus Actions says "You choose when to take a bonus action during your turn, unless the bonus action's timing is specified..."), complete their movement to close with another foe and use their second attack on them. Also during the time between attacks, they can freely talk, shout, hurl insults, etc., up to the time limit their DM imposes.

I agree the tactical decisions in my example are poor, but entirely allowed by the rules, and I can't think of anything else one could do between attacks. I think that movement between attacks is specifically called out as 3.x D&D did not allow that.

 

[Blue]

I do not think this true. A 6th level Bladesinger with two attacks could make one attack on an opponent (but not drop them), move away from them (provoking an Opportunity Attack), use their Reaction to cast shield against that OA, drop their current weapon, use their Use an Object to draw another weapon, use their Bonus Action to activate Bladesong (PHB p.180 under Bonus Actions says "You choose when to take a bonus action during your turn, unless the bonus action's timing is specified..."), complete their movement to close with another foe and use their second attack on them. Also during the time between attacks, they can freely talk, shout, hurl insults, etc., up to the time limit their DM imposes.

Exactly. Yet none of that is that the Attack action is any different than any other action. Just that you can break up all actions with appropriate parts, like the trigger of a Reaction, or the explicit allowance of movement.

This supports what I say. The Attack action has no special ability within itself to be broken up. It is like all other Actions in it's ability to be broken up.

 

[Lyxen]

Exactly. Yet none of that is that the Attack action is any different than any other action. Just that you can break up all actions with appropriate parts, like the trigger of a Reaction, or the explicit allowance of movement.

This supports what I say. The Attack action has no special ability within itself to be broken up. It is like all other Actions in it's ability to be broken up.

100% agreed. Honestly, the system is incredibly open and flexible about what you can combine, interrupt, run in parallel or sequentially, etc.. The limits are few and far between, and most cases of people trying to tell you that you are doing things wrong against the RAW are just readings biases by their own preferences.