Can you ready an action to attack a hidden creature before it attacks you?

Question

The hidden creature is in an adjacent room, he has cunning action, and is taking the hide action every turn after shooting his arrow. He's popping his head, taking the attack action, moving to total cover, and taking the hide action as a bonus action.

The combat has started a few rounds ago and the character that is trying to ready an action is at 1 hp.

Can I ready an an action to shoot an arrow at the hidden creature after he pops his head but before he makes his attack? Considering that he has succeeded on his stealth check?

Answer 1

When you try to hide, make a Dexterity (Stealth) check. Until you are discovered or you stop hiding, that check's total is contested by the Wisdom (Perception) check of any creature that actively searches for signs of your presence. (PHB 177)

So it depends on whether the creature comes out of hiding to attack.

1) If he can stay obscured while making the attack, the result of his stealth check and your opposing perception check stands and he can make his attack unseen. Also note that unless you take an action to try and discover his position, you are not allowed an active perception check, his stealth check is contested by your passive perception. However:

lf you are hidden-both unseen and unheard-when you make an attack, you give away your location when the attack hits or misses. (PHB 195)

So after the attack you would have a chance to attack him with a readied action. Your attack is still with disadvantage (as it is against an unseen target).

2) If he gives up hiding to attack, you automatically notice him and have a chance to use your reaction. He also has to repeat his stealth check if he wishes to hide again.

Answer 2

No.

We can simplify the scenario. Let's focus on the relevant details only:

1. The attacker is already hidden, and they do not do anything else to give their location away prior to attacking you.

2. You are trying to ready an action to attack them after they appear but before they can attack.

The following description of the Ready action states how you can use it (Player's Handbook p. 193, emphasis mine):

Ready. Sometimes you want to get the jump on a foe or wait for a particular circumstance before you act. To do so, you can take the Ready action on your turn, which lets you act using your reaction before the start of your next turn. First, you decide what perceivable circumstance will trigger your reaction. Then, you choose the action you will take in response to that trigger, or you choose to move up to your speed in response to it.

So you can ready an action to trigger on a perceivable circumstance only, meaning that you have to be able to notice the circumstance in order for the readied action to trigger.

The problem is that you won't be able to perceive the enemy coming out of hiding before they make their attack. The following describes attacks from hidden attackers (Player's Handbook p. 194, emphasis mine):

Unseen Attackers and Targets. If you are hidden--both unseen and unheard--when you make an attack, you give away your location when the attack hits or misses.

So their location will not be given away until the attack hits or misses. By the time you perceive that they have come out of hiding to attack you, they have already hit or miss on their attack. Therefore you cannot interrupt them in the attempt.

However...

That's under assumptions 1 and 2 that I stated at the beginning, which basically distilled the important aspects of the scenario you describe.

But, if the hidden attacker did something else prior to their attack to give their location away, something perceivable, then your readied action could trigger before they get to attack. For example, if they give away their location by opening a door or making a loud sound first, you could do so because you would perceive that occurrence prior to their attempt to attack you.

In addition, note that whether the enemy's attack hit or miss you can still follow-up after that with your readied attack action. So, if the enemy in fact missed, your readied attack can still trigger because you perceived their location as soon as they missed. They do not get to stay hidden for free after a miss unless they have a special feature allowing it.

Answer 3

Yes you can, but only so long as the target is plainly visible. Your DM is going to need to make a judgement call here.

Relevant text from Ready Action (emphasis mine):

Ready. Sometimes you want to get the jump on a foe or wait for a particular circumstance before you act. To do so, you can take the Ready action on your turn, which lets you act using your reaction before the start of your next turn. First, you decide what perceivable circumstance will trigger your reaction. Then, you choose the action you will take in response to that trigger, or you choose to move up to your speed in response to it.

If you've noticed a target constantly ducking in and out of battle firing a bow, then this is a perceivable circumstance. Taking aim and waiting to see the target again before firing is the very definition of what a Ready Action is for. The trigger in this case is that they will stick their head out to fire. You are prepared and waiting specifically for that to happen.

Now, the question seems to be, "Is the target considered hidden before it makes it's attack?"

This is entirely dependent on the scenario. Is the door shrouded in dim light or bright light? Does the person with the Ready Action have the ability to see through dim light or darkness?

This is important to know because a target who is successfully hidden doesn't automatically remain so until they attack. They must adhere to areas similar to where they are hiding in order to retain that status. For example, a rogue successfully passing a hide check in the shadows of a keep does not automatically get to walk through the brightly lit courtyard under watchful guards just because they rolled well on their hide check in the shadows. Circumstances changed and the perception required to notice them has dramatically shifted from extremely difficult, to plainly obvious. This means the passive perception of the guards will have no problems spotting the rogue because it's an automatic fail scenario.

So, your scenario may be very similar. If the doorway the target keeps ducking into is lit by torchlight indoors, then the bonus action taken to hide is irrelevant. As soon as they stick their head out of the door and attempt to take aim, the person already waiting for them to specifically do this is going to shoot them first. Remember, the Ready Action happens immediately after the trigger. In this case, it was seeing the target re-enter the room to engage.

In the end, the DM has to decide whether or not the target is going to be benefitting from the hidden status if they step into the doorway. If the answer is yes, then the hidden target will get to fire, and get shot in return because they are now visible. If the answer is no, then they will get shot first because the Ready Action occurs immediately after the trigger.

Answer 4

No, But

...you could do something for that effect.

Rules As Written states that for a character to be hidden it must be unseen and unheard. As it stands, we can asume the enemy is both unseen -behind cover- and unheard -making stealth checks for that and beating passive perception- if we extrapolate it to a real-life encounter, it would be like trying to shoot someone thats behind a small wall. Yes, you saw them ducking behind it, but you cant surely say where they will pop up. On the left corner? right in the middle? Of course, after they pop-up you will see them, but they WILL take the first shot.

Just as the rules says:

lf you are hidden-both unseen and unheard-when you make an attack, **you give away your location when the attack hits or misses **

this so long, is perfectly consistent with the real world that its trying to emulate. However, in the situation you said, the enemy is in another room. I assume that there is either a passage or a door connecting the two rooms, so you can do something of that effect: you could force a situation where he will go out of hiding.

as an example, you can "hug" the wall, aiming for the door/passage and declaring that when you see your enemy pass by, you attack him. If the enemy goes where you are, he will no longer be unseen, so then you will be able to attack him.

again, if we compare this to the real world, it again makes sense, we all have seen/heard examples of characters waiting on the edge of the wall for someone else to come.

of course. if he does not go where you are, you basically "wasted" a turn, but that´s the risk of reading an action.

Answer 5

Yes

Because in the situation described, the character readying the action knows exactly where the archer is, "To the left of that doorway". There's nowhere else the archer can be, there's nowhere else they can shoot from, so their Hide attempt is irrelevant. The readying character can just point their bow at the left side of the doorway and wait. As soon as the archer sticks their head and arm out, the character can shoot them.

If the archer were behind a wall and could therefore pop out anywhere along the length of the wall, then the character can't use the Ready Action, because they does not know exactly where the archer is going to pop up. The archer remains Hidden until the arrow hits or misses.

In other words, Hiding requires uncertainty.