"When you take your action on your turn, you can take one of the actions presented here, an action you gained from your class or a special feature, or an action that you improvise."
So I can in fact, by RAW, ready an action to crawl.
And it's movement, and the DM will resolve it as such.
Going prone takes no movement. So okay. I go prone and crawl. So what.
It's stupid if you want to escape a blast. So your character is purposefully doing something that makes no sense in the world, just so that it can "prove" that the system works ? Is this really what you are advocating ? Just to be sure, you know.
You don't know my character or his perspective. Maybe he's a Shaggy(from Scooby Doo) coward who crawls to get away from things.
I think it's really sad that you have to invent things like that just because you have no ground to stand on in terms of rules.
No. The instant he narrates my taking an action other than what I declared, he has left narration and entered playing my PC. If I say I crawl and he narrates any other form of movement(without mind control or something), then he is in the wrong.
I'm sorry, but no. Let's do an exercise, please describe to me EXACTLY what you describe your character doing.
Constrained by the rules, so if the rules say I get away, then he narrates my getting away. At least during a RAW discussion. DM rulings don't apply here.
So you ARE trying to get away ? THen he describes it exactly the way I did. Because you are crawling as fast as you can, to get away. Otherwise, if you are not crawling as fast as you can to get away, then you are not trying to get away. It can't be both.
Counterspell does not interrupt an instant effect, as I pointed out the last time you tried to give that as an example. Counterspell interrupts the spell while it is being cast. Once the spell is cast and the effect is happening, it's too late for counterspell to do diddley.
I said "counterspell of counterspell".
By the way, this is the Sage Advice on Sentinel. Note the following.
"Does the attack granted by the third benefit of the Sentinel feat take place before or after the triggering attack? The bonus attack takes place after the triggering attack. Here’s why: the feat doesn’t specify the bonus attack’s timing, and when a reaction has no timing specified, the reaction occurs after its trigger finishes (DMG, 252). In contrast, an opportunity attack specifically takes place before its trigger finishes—that is, right before the target creature leaves your reach."
So let's unpack that.
The trigger for Sentinel is when the target within 5 feet of you makes an attack against a target other than you. According to your timing, the attack is the trigger and the attack roll and damage would all be other effects that are interrupted,
No, sorry, this is where, once more, you are wrong. Do you really have to say that "attack roll and damage" are effects ? Where in hell do you get this ? On the contrary, I go by the definition in the PH, what is an attack, page 193/194:
So, OBVIOUSLY, making an attack is all of that, and all of that including the attack roll and and the damage roll is part of making an attack.
The problem is that you don't understand what a ready action is. You only think in game terms and therefore in actions. But, unfortunately for you, the game is more clever than this and requires players to think in character, not as gamers. The triggers are not gamist actions that the character could not perceive like "making an attack roll" or "rolling damage" which has no sense in the game world. The trigger are PERCEIVABLE CIRCUMSTANCES, things that the CHARACTER can see.
So, sorry but no, once more, you have failed to prove anything apart from the fact that you still can't understand the concept of "perceivable circumstance". These are not GAMIING ARTEFACTS, they are actually events in the game world that the characters can perceive.
And by the way, that was one of the problems with 3e, because they used a "condition" as a trigger, which caused many people to use it only for gaming terms, which made no sense in the simulated world. 4e, because it was extremely gamist, made an even worst mistake and used an action as the trigger, because 4e only worked in terms of gaming artefacts (which is why it felt so disconnected to some of us). But 5e did NOT make that mistake, it understands that for a character to react to something, it has to be something that actually is perceivable in HIS world, not in the gaming world of the player.
so the PC with Sentinel would go first. Except it doesn't. The trigger the attack has to finish, which includes rolling to hit and then rolling damage if you do hit. The whole action has to finish.
Ready does not specify the timing. It just says after the trigger finishes. And we know from the Sage Advice(and common sense and the obvious readings of the rules) that means that the teleport and thunder happen before the ready action goes off and the PC readying the action gets to move.
All of that for this ? Again, really sad, my trigger is "the caster disappears", has he finished disappearing ? Yes, because the boom ALSO occurs after he disappears, which proves that it (the disappearance) concludes.
Sorry, but once more, you can muddy it all you want, it does not change the fact that the trigger (the disappearance = the perceivable circumstance) has finished, and that there is no limit as to what can be interrupted.