So have a question on the following situation.
The party was fighting Derro's and the main leader was a necromancer. He was using Fly and up 30 feet above the party.
The one party member is a Bat Shaman and turned into a bat.
Another party member cast Obscuring Mist to help them with the combat.
So now the person playing the Bat Shaman says that when they emerge from the obscuring mist and hit the Derro who was 10' higher than there mist and 20' away from it, that they get sneak attack because the Derro was unaware of the Bat Shaman, and I stated no, because he's in combat with everyone and is aware of his surroundings.
But they stated because he doesn't know where she came from, it's like a surprise and she get's her sneak attack.
Is this correct?
Stated another way, the concealment allows for stealth.
You still need to provide a distraction, get full concealment, or something else in order to go into stealth. If they got one of those, that would allow them to do a stealth check. The check is opposed. If they did that and succeeded at the opposed check, they could get sneak attack.
I'm also unsure where the bat shaman got sneak attack from, are they mutli-classed with rogue?
Also, I'm going to quote the rules on stealth for you:
Check: Your Stealth check is opposed by the Perception check of anyone who might notice you. Creatures that fail to beat your Stealth check are not aware of you and treat you as if you had total concealment. You can move up to half your normal speed and use Stealth at no penalty. When moving at a speed greater than half but less than your normal speed, you take a -5 penalty. It’s impossible to use Stealth while attacking, running, or charging.
Creatures gain a bonus or penalty on Stealth checks based on their size: Fine +16, Diminutive +12, Tiny +8, Small +4, Medium +0, Large -4, Huge -8, Gargantuan -12, Colossal -16.
If people are observing you using any of their senses (but typically sight), you can’t use Stealth. Against most creatures, finding cover or concealment allows you to use Stealth. If your observers are momentarily distracted (such as by a Bluff check), you can attempt to use Stealth. While the others turn their attention from you, you can attempt a Stealth check if you can get to an unobserved place of some kind. This check, however, is made at a –10 penalty because you have to move fast.
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 and attack roll, whether or not the attack is successful (except when sniping as noted below)
So in order to make a sneak attack, they would need to have started their turn using stealth, and they could exist the mist and move toward them (though they can't run or charge, that instantly breaks it) and attack them for one attack and get sneak attack.
But actually being able to make the stealth check might require a bluff check to not see them go into the mist in the first place. It says usually finding cover allows it, and I would probably allow it in this case. But they would have to roll stealth (both the round they enter the mist and at the start of the next round to maintain it) and if they we're undetected the would qualify for sneak attack.
The bat shaman needs to make a stealth check while moving inside the obscuring mist before emerging, opposed by the derro's perception. If the bat shaman succeeds, then the first attack on the derro that round will deny the derro's dexterity, and therefore allow sneak attack. Note that the bat shaman cannot run or charge as that will immediately break stealth, and if moving at greater than half speed, will incur a -5 penalty to his stealth check.
The bluff check is not needed for this specific case. Even if the derro knows exactly where the bat shaman went (inside the obscuring mist), a successful stealth check means that the derro doesn't know when or where the shaman leaves the mist, which is what matters in this scenario.
As above. If the bat shaman started their turn in the mist, the bat shaman makes a Stealth check (opposing the necromancer's Perception check) when moving out of the mist. If successful, and the bat shaman can close the gap in a single move action while using Stealth (usually half speed), then the bat shaman's first attack would deny the opponent's Dexterity bonus to AC and thus qualify for sneak attack. Bluff shouldn't be needed if the character started their turn in the mist.
Does the Derro have Blindsight or something? Does the Shaman?
A misty vapor arises around you. It is stationary. The vapor obscures all sight, including darkvision, beyond 5 feet. A creature 5 feet away has concealment (attacks have a 20% miss chance). Creatures farther away have total concealment (50% miss chance, and the attacker cannot use sight to locate the target).
It looks like the Shaman and the Derro should be Invisible to the each other at distances greater than 5', which means the Derro should be denied its Dex Mod to AC. But the Derro enjoys Total Concealment, too, which means it should suffer no Sneak Attack Damage. SAD doesn't work through Concealment unless the Sneak has some way of mitigating this like Blindsight or something.