There are attacks that target an area (bursts, blasts, etc.); if I use an AOE attack and hit multiple enemies that I have combat advantage against, do I deal sneak attack damage to all of them?
[RPG] Do AOE attacks deal Sneak Attack damage to all targets
dnd-4eroguesneak-attack
Related Solutions
You may only apply Sneak Attack once per turn
However, you may apply it whenever you wish in that turn, so long as you meet the conditions:
When you make an attack with a light blade, a hand crossbow, a shortbow, or a sling and hit an enemy granting combat advantage to you, that enemy takes extra damage based on your level (see the Sneak Attack table). You can deal this extra damage only once per turn.
Given that all uses of powers and class features tend to be optional unless otherwise stated, there is no reason why you cannot take SA on either attack. If you have Slaying Action you may apply it on a second action granted by sneak attack. There are a number of powers that grant sneak attack damage as well.
Coming Out From Behind The Wall
Maybe. Here's the thing. If the Rogue has to come into the open to do this, he's no longer hiding (you can't hide in the open). No spot check is needed to see the Rogue if he just walks out into clear sight of the Ogre, he's no longer hidden. As he's no longer hidden, he'll need some other condition to allow for a Sneak Attack (flanking for example).
This is one of the reasons why Hide In Plain Sight is so good. If you had that, the Rogue could attempt to remain hidden even out in the open and this would work. Shadowdancers for example can stay hidden if they're near a shadow. That would include the shadow of the wall or the Ogre itself, making it a LOT easier to attack while hidden.
Rules Compendium Changes
The Rules Compendium (page 92) adds some extra things to Hide, if you're using it. Those address coming out from hiding a bit differently. In this case the answer would be Yes, if you can make the new Hide check as detailed below.
Move between Cover: If you’re already hiding thanks to cover or concealment, and you have at least 5 ranks in Hide, you can make a Hide check (with a penalty) to try to move across an area that doesn’t offer cover or concealment without revealing yourself. For every 5 ranks in Hide you possess, you can move up to 5 feet between one hiding place and another. For every 5 feet of open space you must cross between hiding places, you take a –5 penalty on your Hide check. Movement speed penalizes the check as normal.
Sneak up from Hiding: You can sneak up on someone after emerging from a hiding place. For every 5 feet of open space between you and the target, you take a –5 penalty on your Hide check. If your Hide check succeeds, your target doesn’t notice you until you attack or perform some other attention-grabbing action. Such a target is treated as being flat-footed with respect to you.
Sniper
Yes. It's specifically mentioned in the Hide skill:
If you’ve already successfully hidden at least 10 feet from your target, you can make one ranged attack, then immediately hide again. You take a -20 penalty on your Hide check to conceal yourself after the shot.
Being aware of someone isn't enough to prevent Sneak Attack. If the spot checks fail against the new hide check, then the Rogue is hidden again and can continue to sneak attack.
Hiding and Sneak Attack
Yes, being hidden with Hide makes you effectively invisible, which normally allows Sneak Attack. Again from the Rules Compendium (p. 92):
If you’re successfully hidden with respect to another creature, that creature is flat-footed with respect to you. That creature treats you as if you were invisible (see page 76).
Best Answer
No.
From the Compendium (emphasis mine):
Sneak attack can only be applied once per turn, and is applied when you hit the target. Once you hit one of the targets and apply sneak attack to it, you no longer have sneak attack available to apply to other targets that round.