I view every attack roll or saving throw as a response to a singular event. Even in the days of one minute rounds, I viewed the attack roll as that moment when you actually got a real chance to do damage. I would never view 10 points of damage as 10 minor hits over the course of that time. Each hit is a single hit in my mind. I just believe there are feints and maneuvering attacks all around the real attack.
So when damage is rolled there is no chance to change that fact. Something like DR is okay because it is part of the damage roll equation. The mind of the character cannot be part of that equation though. Because if I choose parry when I take 10 damage and choose not to waste my parry on 5 damage then I'm using knowledge that is only known after the fact. If I took the damage though then how am I undoing it.
Obviously if you had a spell that let you see the future that might be different but it would have to be something like that. No normal method of time travel calculation is possible.
This is interesting and I think instructive to the variance within playstyles. So your position here is indeed what I thought it wasn't. You take every roll of the dice as an immediate and irrevocable fact established in the gameworld. You take this as an established fact, even (a) when the time continuum that this fortune resolution of action declaration is mediating is large and abstract and (b) before relevant units (HP totals and/or tables) are consulted for final results - meaning the damage-in is established and it has meaning on its own before comparing to HP totals or the "in-fiction" result has meaning before the (immediate interrupt) consultation of the table rolled against takes place?
I guess I've got a few further questions then:
1) What happens when you're at the table and the information you conveyed as GM is misperceived or corrupt/inaccurate with respect to past events and play is
interrupted by this realization. Is the GM-understood (but erroneous) PC action declaration then overturned to the correct one or must it stay as it was regardless of the misperception? Is the continuity or corrupt information resolved/fixed and then play continues sensibly or is it mandate that these are now irrevocable established facts in the gameworld?
2) Reaction/Interrupt mechanics work in the same vein as the consultation of tables and total HP (post damage roll) do. They are an intermediary to reconcile "what just happened." Assuming you describe HP damage before consulting the intermediary of HP totals, what happens when your description of the damage-in is incoherent with respect to those HP totals? What happens when you roll on a table when populating a dungeon and you feel the results strain credulity? Its been established, so presumably you're going to go with it and find a way to make it work?
3) Regarding the continuum of time in a 6 second or even 1 minute round of combat. In anything in life, people are reorienting themselves constantly, making real-time observations, subsequent real-time decisions, and subsequent real-time actions. Presumably you're ok with the AD&D parry rule whereby you declare the action at the beginning of the round for the entirety of that abstract stretch of time; forgo attacks to make attackers incur a penalty "to hit" equal to your own "to hit." With respect to both (i) player agency (maximization of informed player-side decision-making based on coherent/consistent GM conveyance and the intuitiveness of the system's machinery) and (ii) the way decision-making occurs in real-time in real life (which flows into i), does this parry mechanic make more or less sense than an immediate action parry triggered by:
"you are (
going/sure to be) hit by an attack (
if you don't do something about it)".
The parenthesis are mine, of course. Those implications wouldn't be included in a feature/ability block (or at least they shouldn't be) because they would overburden the rules text with the (presumably) obvious.
Would you be more comfortable with reaction/interrupt mechanics if the implications in the parentheses were made explicit in the text? Does having a bucket of reactions/interrupts to "
do something about it" bother you because you feel it equals precognition (which, to be honest with you, is pretty much what happens in martial exchanges - borderline precognition because your OODA loop spits out a permutation that perfectly predicts what your opponent does and you're able to react in space and in real-time as if you "had precognition")? Personally, that improves the play experience and makes it much more like the real-time decision-making that occurs in our world (which is presumably how biological organisms observe, orient, decide, and act in our fantasy worlds).