Please explain to me how Hide works

[Juzam]

I've been DMing and playing 3.5 since it came out--and 3.0 before that.

I always thought I understood how Hide worked, but recently have come to be greatly confused by it. In particular, situations in which a target is denied the benefit of dexterity as a result of the attacker's being hidden from the target.

I apologize if this question has been previously asked and addressed, but I've searched the internet for hours and haven't found an explanation that solves my puzzlement over how Hide is supposed to work.

OK, it makes sense with the most straightforward examples. Let's say the target does not see the attacker at all--the target has improved invisibility, or there is total darkness and the attacker can see in the dark but the target can't (and has no other relevant senses or means of detection that could detect the attacker).

It makes perfect sense that the attack denies the target the benefit of dexterity bonus to AC in those examples. (A really high spot check could allow seeing the invisible target though and prevent this.)

Now suppose the target comes to a position where the attacker is hidden behind cover and laying in ambush. The attacker remains behind cover and makes an attack on the target. The target gets a spot check of course. If the target has failed to detect the attacker, so that the attacker is hidden with respect to the target, the target is denied dexterity bonus to AC.

There is a rule that there is a -20 penalty to Hide while attacking, running, or charging. But, if I understand correctly, that -20 penalty is to Hide is basically to remain hidden even after the attack. (Or to become hidden if not previously hidden.) In other words, in my example in the last paragraph, does the attacker take a -20 penalty in order for the target to be denied the benefit of dexterity to AC, since he is attacking? Or is the -20 not required in order for the target to be denied dexterity for the attack, but only to remain hidden after the attack? If the -20 is not required for the attack, but only to remain hidden after the attack, what about a full attack--can the attacker make a full attack without requiring a -20 penalty except to remain hidden after the attack?

I think the answer is that the attacker was already "hidden" before making the attack (relative to the target, if the target failed the opposed Spot-Hide check), and if the attacker was successfully "hidden" before the attack, the target is denied dex bonus to AC. But attacking "cancelled" the effect that the attacker was hiding--however the attacker can hide again while attacking, but take a -20 penalty. By attacking, the fact that the attacker was "hidden" is now "cancelled", effective after the attack is complete, but the attacker can make a new hide check at -20 to hide during the attack in order to remain hidden after the attack is over. Do I have that right?

I think the last example was slightly simpler than what I am leading up to, because the attacker remained in cover. Let's take the same example where the attacker is hidden behind cover and laying in ambush, but takes a 5 foot step out from behind cover and then makes a full attack. Does that attack cause the target to be denied dexterity bonus to AC?

There is a rule about sniping, but that rule clarifies that I can take a move action to hide after making a ranged attack, at a -20 penalty. But I don't think that really clarifies what happens during the attack itself.

There is a rule to "Sneak up from Hiding" (page 92, Rules Compendium) that may be relevant. It says that you can sneak up on someone from a hiding place, and for every 5 feet of open space between you and the target, you take a -5 penalty on your Hide check.

This rule seems to presume a melee attack. If an attacker emerges 5 feet from a hiding spot and then makes a full ranged attack, is that basically "sneaking up" 5 feet, so that you would need to make a new hide check at -5 in order to deny the target's dexterity bonus to AC?

The other thing that confuses me is how attempting to get attacks that deny the target their dexterity modifier due to being hidden from target interact with "hiding while observed".

By "hiding while observed", I mean the rule that, "If someone is observing you, even casually, you can't hide. You can run around a corner or behind cover so that you're out of sight and then hide, but the others then know at least where you went."

If I'm trying to get an attack while denying my target a dexterity bonus to AC, I don't care if he knows where I went--I just want to be hidden with respect to the target to deny my target a dexterity bonus to AC.

If I hide while observed, so that I am hidden but my opponent "knows where I went", is my opponent still denied a bonus to AC when I attack him? Does it matter if my opponent expects this tactic, or whether there are multiple positions that I can return to sight?

For example, let's say I have 60 feet of movement, and use a move action to go around the corner, and and continuing my 60 feet of movement, I reverse directions and come just barely back around the corner, and my opponent expects me to do this--is my opponent denied his dexterity bonus to AC?

What if I hold my tower shield in front of me, giving me total cover, then drop it as a free action and take an attack? What if I hide behind a tree, am observed while doing so, but I take cover behind the tree and then attack--my opponent "knew where I was" but I was still hidden from him--is my opponent denied his dexterity modifier to AC when I attack (assuming he fails the opposed spot-hide check)?

In the above examples, it seems sort of unintuitive that dexterity bonus would be denied. But what if, for example, I take crouch to take cover behind a very long wall, completely blocking line of sight to my target, crouch along the wall a long distance with my great speed, then peak out from behind the wall at a much different place than I went behind the wall. The target knows I went behind the wall but doesn't know where I will peak out from behind the wall to make an attack. Does that make a differences, versus say running around the corner and then running back from the exact same spot? What if I fly with perfectly maneuverability, and instead of remaining in cover behind the wall, I fly just above it at an unexpected position--is my opponent still denied dex bonus to AC if my opponent fails a spot check--and does this count as 5 feet of "sneaking up" causing a -5 penalty on my hide check?

Obviously, a DM can make house rules and judgement calls, but I'm at least trying to figure out what the actual rules are as a baseline.

[Flickerdart]

When a character jumps out from the bushes and fills an unaware enemy full of holes, the enemy is denied Dex to AC as a result of being flat-footed, since the attack happens in the surprise round before he got to act.

[CRtwenty]

The -20 penalty would only be applied if the character was trying to remain hidden while doing the action. IE an Assassin is hiding behind a curtain, launches his death attack to kill a target whose walking with his guards and retreats behind the curtain without being seen by the guards.

A regular Hide check would allow the Rogue to catch his target flat footed, but would not allow him to remain hidden afterwards. IE a Rogue is hiding behind a crate, when an Ogre and two Orcs walk by he pops out and sneak attacks the Ogre, dropping it. The two Orcs now initiate combat as normal.

[ArcturusV]

Same logic applies to midbattle stuff. Say a fight is already going on, and thus there is no surprise round to factor in. If you have concealment of some type, or Hide in Plain Sight, etc, you can hide. If you beat their spot checks, you're hidden (Though you won't/shouldn't know if you were actually successful). Then your rogue/assassin/whatever could pop out of your hiding spot (Which may not be where cover is, as you can move afterwards and remain hidden), and possibly get a Sneak Attack/Sudden Strike. But you'd be spotted unless you beat their spot check with a -20 to your own Hide. So then you'd have to scramble to cover again, pass a hide check, and do it again.

Which is why I generally don't like Ranged Sneak Attackers, as it kinda locks you into a 1 on, 1 off pattern instead of the Always On that Flanking in melee has (Unless you have a really high Hide Check or shenanigans in particular that let you go on with this).

[Curmudgeon]

I think the answer is that the attacker was already "hidden" before making the attack (relative to the target, if the target failed the opposed Spot-Hide check), and if the attacker was successfully "hidden" before the attack, the target is denied dex bonus to AC. But attacking "cancelled" the effect that the attacker was hiding--however the attacker can hide again while attacking, but take a -20 penalty. ... Do I have that right?
Yes, you're on track so far. Note that to Hide while attacking, the attacker must still satisfy all the Hide requirements at that time. If they've got cover or concealment that's one requirement. If they were already hidden that satisfies another requirement (not being observed).

I think the last example was slightly simpler than what I am leading up to, because the attacker remained in cover. Let's take the same example where the attacker is hidden behind cover and laying in ambush, but takes a 5 foot step out from behind cover and then makes a full attack. Does that attack cause the target to be denied dexterity bonus to AC? That depends on how the DM interprets the following highlighted word:
Trying to spot something you failed to see previously is a move action. The DM could treat "something" anywhere in the range of "the same character" to "the same character in the same place doing (or not doing) the same thing in the same manner". If the DM picks the latter one, then you'll need to make the Hide check on the first swing of the full attack, and use the same sort of attack each swing, to remain hidden throughout the full attack. If the DM picks the former, you're hidden throughout if you just succeed on the Hide check while moving 5'.

There is a rule about sniping, but ...
Ignore Sniping entirely unless you're making ranged attacks exactly following the Sniping procedure. Those rules apply to no other scenarios.

There is a rule to "Sneak up from Hiding" (page 92, Rules Compendium) that may be relevant. It says that you can sneak up on someone from a hiding place, and for every 5 feet of open space between you and the target, you take a -5 penalty on your Hide check.
Yes, and this is also required in the previous situation where you moved 5' out of hiding. You'll also need to add another -5 penalty for moving at greater than half speed (because half speed would only make for a 2.5' step, and you'd never get out of your square).

This rule seems to presume a melee attack. If an attacker emerges 5 feet from a hiding spot and then makes a full ranged attack, is that basically "sneaking up" 5 feet, so that you would need to make a new hide check at -5 in order to deny the target's dexterity bonus to AC? Every time you need to make a Hide check you have to satisfy the requirements to use the skill. In this scenario your new location would still need to offer cover/concealment and you'd still need to be unobserved — if you were required to make any new Hide checks. Again, it's how the DM interprets "something" for the Spot rules requiring move action retries that will determine whether you can hope to succeed if you don't have cover/concealment in the new location. If the enemy needs to use a move action to Spot you, they can't do that until their next turn; you get to finish your full attack without being seen. But there's no requirement to make melee attacks rather than ranged.

The other thing that confuses me is how attempting to get attacks that deny the target their dexterity modifier due to being hidden from target interact with "hiding while observed".
You simply can't Hide while being observed. If an enemy has been watching you, simple cover or simple concealment isn't going to help you. You need a complete loss of line of sight (at which point there's no need, and no option, to Hide) before you can then move to a place of ordinary cover/concealment and try to Hide again. Moving behind a single tree for ordinary cover does nothing for you. Moving behind a thick stand of trees, after which you have the option to peek out again, would afford a new opportunity to Hide; after all, there's no guarantee that you will peek out again, and there's no guarantee of where you might choose to do so. The enemy must completely lose sight of you before you can satisfy the "not being observed" requirement necessary to be allowed to Hide.

[TuggyNE]

My earlier thread on this general subject may also be of service.