My question is a generalization of this one: Can you interrupt an action with a Ready Action?

When you ready an action in Pathfinder, the readied player jumps in an instant before the trigger happens (emphasis mine):

Readying an Action

You can ready a standard action, a move action, a swift action, or a free action. To do so, specify the action you will take and the conditions under which you will take it. Then, anytime before your next action, you may take the readied action in response to that condition. The action occurs just before the action that triggers it. If the triggered action is part of another character's activities, you interrupt the other character. Assuming he is still capable of doing so, he continues his actions once you complete your readied action. Your initiative result changes. For the rest of the encounter, your initiative result is the count on which you took the readied action, and you act immediately ahead of the character whose action triggered your readied action.

Are actions atomic (in the computer science sense)?

For each of the different kinds of actions in Pathfinder (Standard, Move, Full-round, Swift, Immediate, Free, and any others you can think of), can one character perform their readied action in the middle of another character's action?

Examples by intuition:

  • It makes sense in the question linked above for a readied action to interrupt a move action (e.g. wolf wants to move past me, so I ready myself to sidestep when the wolf comes within 5').
  • It makes sense that a person could ready themselves to shoot an arrow when an NPC attempts to light a torch (full-round action).
  • It doesn't make sense to interrupt an immediate action (e.g. person says a word, ceace concentrating on a spell, etc.).

1 Answer 1


No, actions are not atomic. There are numerous cases in the rules where one action can take place in the middle of another, e.g.

  • You can take a 5-ft. step (a type of free action) in between two attacks of a full attack (a type of full-round action).

  • The Spring Attack feat allows you to use an attack action (a type of standard action) in the middle of your move action (which you may then resume afterwards).

  • Enemies’ attacks of opportunity (which does not really use an action, or arguably constitutes its own kind of action) that you provoke by moving interrupt your movement (typically but not strictly via move action), which you may then resume after the attack of opportunity has been resolved.

Readied actions, like immediate actions, interrupt other things going on. They may take place in the middle of another action.

In all of these cases, the interrupted action is put on hold, and the interrupting action is resolved entirely before resuming the interrupted action. These can be nested indefinitely.

Now then, the game does not have strict timing rules for “generic” kinds of interruptions like readied and immediate actions (attacks of opportunity, Spring Attack, etc. do have fairly detailed rules). This is largely left up to the GM. In the case of immediate actions, their timing is defined largely by the individual action’s text, though these are not always entirely clear. For readied actions (and the contingency spell, and others), the triggering condition is defined by the player and adjudicated by the GM, so the precise moment is always kind of questionable. Generally speaking, it’s accepted that while you can have a trigger relating to some roll or outcome, by the time a roll is done, it is too late to prevent the outcome of that roll entirely (instead you react to that outcome the moment it’s in place). If you wish to prevent something, you have to react prior to it being rolled.

  • \$\begingroup\$ How do you reconcile the provided example of reacting to a word being spoken? If a readied action "occurs just before the action that triggers it" then how can you ready to attack when your teammate shouts "Attack!"? In that case, you would have attacked before the "Attack!" command was even shouted. Genuinely curious because I never noticed the "occurs just before" language of readied actions before. \$\endgroup\$ Nov 11, 2016 at 21:30
  • \$\begingroup\$ @LegendaryDude the wording exists to avoid abuse-cases; it would be better stated as "before the action has consequences," or "before the trigger completes." The edge-case that is being subverted here is "ready a trip for when the enemy stands up." (the same reason attacks of opportunity occur before the provoking action completes- so you can't trip-lock someone) So actions readied for a command to be given would occur before the "ATTACK!" shout is over. If the shout was a command word, its effects would resolve after the readied actions. \$\endgroup\$
    – Delioth
    Nov 11, 2016 at 21:40
  • 1
    \$\begingroup\$ LegendaryDude: I think this is best thought of as a (corner) case where we have to accept that the mechanics are an abstraction of reality, not a perfect model. To extend your example, how could the actor reliably expend his readied action when the speaker shouts "ATTACK!" but reliably NOT expend it if the speaker unexpectedly yells "ATTRACT!" instead? Mechanically, the readied action happens first, but thematically, it would happen AS the word is spoken, or shortly after (ie: before anything else important happens, as Delioth says.) \$\endgroup\$
    – Steve-O
    Nov 11, 2016 at 21:59
  • \$\begingroup\$ Think of it as a player losing the ability to perform any action on a turn, but on the next turn his character is able to react in a specific anticipating way to a predicted enemy action. In other words, if he anticipates a trap, his lost turn allows him to perform a specified action like jump backwards if a trap goes off. Of course, if someone casts a spell at him, or the trap doesn't go off, he has wasted his turn for nothing. If a player anticipates a specific attack, allowing him to spend/waste the use of an earlier turn on avoiding (or reducing the effect of) that attack is reasonable. \$\endgroup\$ Nov 13, 2016 at 16:10
  • \$\begingroup\$ @Delioth You actually CAN trip lock someone with readied actions by selecting the right trigger. You just can't use the AoO provoked by standing up. \$\endgroup\$
    – Umbranus
    Nov 15, 2016 at 7:12

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