Aside: there's an official ruling the Sage Advice Compendium that this isn't how the game is designed to work.
Oh, really? Which ruling is that? I didn’t know there was one about how the whole game was designed to work. Btw, did you know this thread is about the recent update to the Sage Advice Compendium?
Can you apply this timey-wimey logic to the Ranger's Natural Explorer, specifically this sentence:
"If you are traveling alone, you can move stealthily at a normal pace."
This sentence has the same structure as Shield Master's bonus action, specifically "if you X, you can Y". You're stating that you can Y, as long as X is eventually true, right?
Take out the word
eventually, and you’ve got it, X for the Shield Master shove being “you take the Attack action on your turn”. If you do, then you can (on your turn).
So, why can't I use this rule to stealth at normal pace whenever I want, because I declare that I'll travel alone at some point in the future?
Because the condition isn’t “you will travel alone at some point in the future”. It’s “you
are traveling alone,” which implies that the action is ongoing and concurrent with the benefit being gained. Verb tense matters.
Or, let's use another example from Shield Master itself:
"If you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you can use your reaction to take no damage if you succeed on the saving throw, interposing your shield between yourself and the source of the effect."
Let's say I get hit with a Cone of Cold, and make the CON saving throw. Why can't I use the "Y" portion of this (use my reaction to halve the damage) because I declare that I'm going to get targeted by an effect that allows me to make a DEX save for half damage later on my turn (i.e. the "X" portion)?
There are a few reasons why I don’t think you can do that. First, “the saving throw” obviously refers back to the DEX saving throw in the condition, so you wouldn’t be eligible to receive this benefit on a CON saving throw. Second, a reaction, by definition, "is an instant response to a trigger of some kind," and in this case the trigger is the situation described in the condition. You can't respond to something that hasn't happened yet. Also, the verb tense used doesn't agree with your reading. I.e., "are subjected to" is not "will be subjected to".
If there's no strict timing requirement between X and Y like you're claiming, then I should be able to just put my shield in front of any effect that has me make a saving throw and take no damage when I succeed.
It's a conditional statement. X must be true for Y to be true. Any effect that allows a saving throw is not sufficient. It must be an effect that allows a DEX saving throw, and you must be subjected to it.
At the end of the turn, how do we resolve this Schrodinger's Reaction? I can't just go back and turn a bonus action into an action here, like you're suggesting we do with the Shield Master shove case.
For the umpteenth time, that's a blatant mischaracterization of what I'm suggesting, and in this case, taking no damage instead of half damage isn't something you can normally do, whereas shoving a creature is.
That's not now conditions work. The trigger condition is true from the point at which it becomes true until the end of your turn. You can't go back in time and say the trigger was true before the triggering event happened. D&D 5E is a sequential turn-based game, and as a result, timing and order of events matters.
If "you take the Attack action on your turn" is true, then that's something that's true of your turn in its entirety. It can't be both true of your turn and not true of the same turn. You either take the Attack action on your turn, or you don't take the Attack action on your turn. If I have a turn in which I take the Attack action, then I can use a bonus action to shove a creature on that turn.
Again, let's apply your logic to other triggered events.
Natural Explorer: "If you are traveling alone, you can move stealthily at a normal pace." 3 in-game years from now, my character will travel alone for day. Therefore, this trigger has been satisfied, and retroactively applies until the beginning of time because the rule doesn't explicitly say my turn. Thus, this rule says my character can simply move stealthily at full pace, period.
No, it doesn't because traveling alone three years from now doesn't make "you are traveling alone" true.
Shield Master: "If you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you can use your reaction to take no damage if you succeed on the saving throw, interposing your shield between yourself and the source of the effect." I can use my shield to take zero damage any time I succeed on a saving throw, because at some point in the future I'll make a Dex save. Because I'll make that Dex save at some point in the future, the triggering condition is true and thus I can retroactively get the benefit of this feature.
No, you can't because being subjected to an effect that allows you to make a DEX save for half damage at some future time doesn't make "you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage" true.
As you can see, this is nonsense, right?
Your examples are nonsense that needlessly bogs down the conversation. It is not nonsense, however, that taking the Attack action at any time on your turn makes "you take the Attack action on your turn" true.
