Popping Out - If you emerge from hiding during combat, what happens in Pathfinder First Edition?
Back in the Gygaxian yore of First Edition days, a thief (they were not called rogues back then) would move silently up to a foe and backstab the enemy! But what about in modern editions? Well, let's ignore Fifth for now, and focus on my own favorite kind of Dungeons and Dragons, Third Edition, by way of its bastard offspring, Pathfinder 1E.
Total cover and total concealment let you hide completely, with no need for a stealth check, because your enemy has zero line of sight to you -- it is still valuable to make stealth checks in total concealment, so that enemies have more trouble pinpointing your square by, say, hearing. You cannot direct an attack at a creature so protected (you can guess/sense the presence of a creature with total concealment and then attack into that square, usually with a 50% miss chance.)
So say you are hidden with total cov/con, to coin a phrase, and you emerge using stealth. What happens? The rules cover two cases. First, if you start an encounter hiding, and move out of hiding to attack.
Surprise: When a combat starts, if you are not aware of your opponents and they are aware of you, you're surprised. ... Combatants who are unaware at the start of battle don't get to act in the surprise round. Unaware combatants are flat-footed because they have not acted yet, so they lose any Dexterity bonus to AC.
Second, if you start making stealth checks and then move out stealthily and look for a new place to hide, maybe with only regular cov/con. That's called "Breaking Stealth."
Breaking Stealth: When you start your turn using Stealth, you can leave cover or concealment and remain unobserved as long as you succeed at a Stealth check and end your turn in cover or concealment. Your Stealth immediately ends after you make an attack roll, whether or not the attack is successful (except when sniping as noted below).
It's pretty clear. If you start a fight hidden by stealth and your foe is unaware of you, when you attack, they are flat-footed and lose their dex bonus to AC.
And if you are hiding in the middle of a fight, you can sneak from one hiding spot to another and stay undetected if your stealth checks succeed.
BUT! What if you are hiding in the middle of a fight, and you sneak out of hiding, but instead of finding a new hiding spot, you attack? What happens?
A friend on a rules discussion message board recently posted this example: "Say you're fighting some goblins and the goblin shaman brings up an Obscuring Mist. Would any PC attacked by goblins that charges out of the mist to attack not get thier DEX bonus to their AC? If that were the case, I'm pretty sure that would be mentioned under the Obscuring Mist spell."
Well, if the goblins charge out, they are not being stealthy. The stealth rules say so specifically: "It's impossible to use Stealth while attacking, running, or charging." (Side note: In 3E it is not impossible, just "practically impossible," which means you can try at a -20 on the check.)
But what if they were using stealth in the mist the prior round, then they sneak out, moving silently up to a foe, and stabbing them in the back? Well, the rules quoted above imply an answer: "Your Stealth immediately ends after you make an attack roll." That means, before you attack, you CAN use stealth to sneak up and attack. If your stealth beats your target's perception, then you can attack (first attack only) with the benefit of being hidden, that is, your target loses its dex bonus, and if you are a rogue, you can sneak attack.
That's my interpretation and answer to the question ... if you are hidden, can you sneak forward and attack your foe with the benefit of being hidden? Yes, if your stealth is good enough!
Now, let's get fancy. If you are an arcane trickster (or anybody using stealth with some magic capability), what if instead of an obscuring mist, it is a silent image of obscuring mist?
In this case, the arcane trickster within the mist does not have to emerge to make a sneak attack. You can see your foe clearly, even though they cannot see you. Note that per the rules, "Creatures encountering an illusion usually do not receive saving throws to recognize it as illusory until they study it carefully* or interact with it in some fashion" ... but if they get a save, they still won't see it as fake if they fail the save.
Of course, anyone who enters or touches the mist (or any illusion) is interacting with it, and gets a save, no action needed.
So, arcane trickster within illusionary fog, making stealth checks, attacking out with arrows or rays, and unseen if the target does not get a save or if they fail a save. In this case, the trickster does not have to emerge to get a sneak attack, but instead gets to keep on making them so long as they have the total concealment of the spell. And so long as they stay within the 30 ft range of sneak attacks. Outside 30 ft, the target still loses its dex bonus to AC but is not subject to sneak attacks.
It is worth mentioning that a dwarf rogue in total darkness (with darkvision) gains the same benefit against a human (without darkvision). He remains hidden -- even without stealth checks -- because he has total concealment.
Another similar situation is attacking while affected by Greater Invisibility. (Note that this is official Per Word of God from Paizo. Also see a similar comment here applying more generally, not just to greater invisibility.)
It is worth noting that nowhere in the rules does it say, "You can emerge from hiding, stealth up to a foe, and sneak attack it." Nor does it say, "If you have total concealment so that your foe cannot see you, but you can see your foe clearly, then every attack you make is a sneak attack." Rather, what the rogue rules say is: "If a rogue can catch an opponent when he is unable to defend himself effectively from her attack, she can strike a vital spot for extra damage. The rogue's attack deals extra damage anytime her target would be denied a Dexterity bonus to AC ... The rogue must be able to see the target well enough to pick out a vital spot and must be able to reach such a spot. A rogue cannot sneak attack while striking a creature with concealment." So your mileage may vary, especially if your DM does not want you to get those sweet sweet sneak attacks.
Also, if you found this screed at all compelling, you may be interested if how I have revised the Stealth skill for my verison of D&D, called Labyrinths & Liontaurs.
*Note, per the Perception skill rules, "Intentionally searching for stimulus is a move action."
Creative commons photo credit, with thanks: pxhere.com.