# When does a reaction happen if the trigger is movement?

I realize there are a bunch of these questions about the ready action but I couldn't find one that answers what I have in mind.

I know by RAW the reaction happens after the trigger finishes but how does that work with movement?

1. What if I specify the distance that must be travelled for the reaction to occur?

For example, if the trigger is "when that creature has moved 10 feet" but the creature's movement that turn is to be 20 feet without any breaks - do I react at 10 feet or after the intended movement of 20 feet is completed?

2. What if the trigger was only specified as movement by an opponent?

For example, if the trigger is "when that creature moves" but the creature will move a total of 30 feet and plans to break for an attack in the middle of that movement, when do I react? Does the reaction occur after the first 15 feet but before the attack? Does it wait until the whole 30 feet movement is finished?

Even though I've used "I" as the player, I am asking as a DM. Is there something in RAW I'm missing or are there any designer comments on this by chance?

# Always after the trigger, but you don't have to wait for enemy to complete their intended movement

When the trigger occurs, you can either take your reaction right after the trigger finishes or ignore the trigger.

A reaction always occurs after its trigger unless a rule specifically says otherwise.

It is fine if the attack comes in the middle of the enemy's intended movement just as long as the trigger has been satisfied. There is no rule that says that movement must be completed as a block and that nothing can interrupt it. On the contrary, the player can break up their own action in any number of ways. Thus, it is very reasonable to say that enemy reaction can also trigger in the middle of movement as well. Just like an opportunity attack, once the attack has completed the enemy may continue moving if they are able.

### Specific cases

1. Immediately after the enemy has moved 10 feet, you may take your attack, even if they plan on moving more.
2. Immediately after the enemy moves at all, you may attack.

### Minimum movement should be 5 feet on a grid

If you are using a grid, I would recommend breaking up the movement into 5 foot chunks especially for things like the second trigger since since that is the smallest tactical movement the rules are really able to handle.

If you are not using a grid, then timings are obviously a bit less precise so just allow triggers whenever, narratively, the character has moved a significant amount.

### You can ignore triggers as well

It is worth noting that you may ignore any number of triggers but still choose to react on a later trigger as long as it is before the start of your next turn. For example, for your case 2, once the enemy moves 5 feet your reaction would trigger (assuming they were in range), but also every 5 feet thereafter until you choose to act on it (as long as you don't use your reaction in other ways and it is before the start of your next turn and the enemy is still a valid target for attack).

As Jeremy Crawford has said:

Ready action. The rules says you can ignore the trigger, because yes, you can ignore it. You can try again if it is open-ended enough.

### Most of the time, it is going to be better to keep your triggers more open-ended

Since you can ignore triggers and still use them later in the turn (assuming you worded the trigger to not exclude that possibility) there is no real reason to be super specific when you word your triggers. "When the enemy moves towards me" triggers much more often then "After the enemy moves 10 feet" and you make no sacrifices in choosing it over the more specific one. As long as you word things the way you want, you should be able to make do with a more general trigger in most cases.

• This is an interesting take. I like the idea that trigger can refer to a part of an action rather than being the entire action itself (eg more 20ft). This leads to interesting situations such as "when an enemy starts to attack me, I push the enemy back" or "when I am hit with an attack, I push the enemy back". You could certainly be quite disrupting with these kinds of logic. Apr 23, 2020 at 7:39
• @user-63873687: Well, I think certain things can be interrupted and others can't really be interrupted. Each bit of movement is its own thing, and nothing prevents you from taking a reaction in between a creature moving from point A to point B and moving from point B to point C - but you can't normally do something in between an attack hitting and the effects of the attack taking place (barring a spell like shield that specifically has that timing). Apr 23, 2020 at 20:00
• @V2Blast I'm not sure I understand. You can't "normally" do anything between a creature moving from point A to point B either. That's the whole point of readying an action is it not? To me, the fact that shield has it as a valid trigger should also be an indication that it is a valid trigger for ready! Apr 24, 2020 at 1:08
• @user-63873687: No, I mean there's no perceptible step between a hit and the effects of that hit. Shield triggers on a hit, but it's magic that specifically says it can change the outcome to a miss. In contrast, the Ready action specifically requires a perceptible circumstance, and I don't think "after the hit but before its effects" is perceptible. Also, reactions happen after their triggers unless the rules explicitly say otherwise (like shield or opportunity attacks) - and the Ready action is not one of those exceptions. Apr 24, 2020 at 7:29
• @user-63873687: In short, you can't "cancel" an attack by trying to shove them after they've started to attack you or after they hit you. You can shove them when they walk up to you, but they can always move up to you again afterwards if you still have movement left to use. Rules designer Jeremy Crawford (unofficially) confirms my interpretation in this pair of tweets from May 2017. Apr 24, 2020 at 7:34