# Does an opportunity attack happen before or after the creature moves?

Well I have a fighter with the "sentinel" trait - which says a creature's movement becomes zero when hit with an opportunity attack.

Now I wonder, if a creature moves out of "reach" where does it end up (considering I do hit)? Does my attack make the creature stop dead inside or just outside my reach?

### Opportunity Attacks occur before the target leaves your reach.

The rules for opportunity attacks state:

The attack occurs right before the creature leaves your reach.

And Sentinel states:

When you hit a creature with an opportunity attack, the creature's speed becomes 0 for the rest of the turn.

Since it happens before they leave your reach, their speed becomes 0 while they are still within your reach.

Now, if you are playing on a grid, the rules break your movement down into five foot chunks:

Speed. Rather than moving foot by foot, move square by square on the grid. This means you use your speed in 5-foot segments. This is particularly easy if you translate your speed into squares by dividing the speed by 5. For example, a speed of 30 feet translates into a speed of 6 squares.

Using this rule, the target would simply remain in the square they are in. However, if you are measuring movement foot-by-foot, then the target would be stopped when they are exactly five feet from you, but I've never played at a table that used that level of granularity for movement. I've always played that sentinel just prevents the target from moving entirely, as it would be on a grid, even when not playing on a grid. It's simpler that way.

• Note sure it deserves inclusion, but the original wording is non-functionally different, reading: "The attack interrupts the provoking creature's movement, occurring right before the creature leaves your reach." Jul 26, 2022 at 12:52
• About playing without a grid, even without those rules, a creature has a “space” which is generally in 5-foot-square increments. So I think your suggestion to avoid such granularity is supported, at least for the movement and position of creatures larger than Tiny. Jul 26, 2022 at 15:09

## The creature stays inside your reach

The rules on Opportunity Attack say:

(…)You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach.(…)

The Sentinel feat then states:

(…)When you hit a creature with an opportunity attack, the creature's speed becomes 0 for the rest of the turn.(…)

This stops the creature's movement right at the point your attack hits. Therefore, the creature remains within your reach.