Would like to seek advice on how to adjudicate when one group (Group A) is attempting to ambush another (Group B). Assume that everyone in Group A is aware of Group B, but not vice versa. Thus, RAW, everyone in Group A should get to act in the surprise round. Issue is how to resolve for Group B.
If everyone in Group A had the same stealth bonus (e.g. same creature type), then it's quite straightforward. The stealth roll by Group A would be the perception DC for Group B. Whoever in Group B meets the DC would get to act in the surprise round, while the rest won't.
However, what happens if those in Group A have different stealth bonus? I see two possibilities:
1. The stealth roll by Group A is based on the lowest stealth bonus in that group. Otherwise, resolve as above.
2. Everyone in Group A makes a stealth roll. Whoever in Group B makes a perception roll higher than the lowest stealth roll would get to act in the surprise round, but only against those in Group A whom they beat the stealth roll of.
Option #1 is easier to manage, but can be unfair to those with high stealth bonus. "Hey, yes our group was given away by that clunky paladin, but I managed to stay hidden!" On the other hand, option #2 seems more correct RAW, but would be a nightmare to keep track of the individual rolls. Also, it lends itself to metagaming. "Yes, I didn't see the rogue behind the corner, but I was going to cast a fireball at that general location anyway."
On top of that, what if Group A decides to distance themselves such that those with high stealth bonus are further in front? Then reasonably the stealth roll should be just based on the stealthy ones. But does that mean those in Group A who hung back forgo their opportunity to act in the surprise round? But by RAW, they are aware of Group B so should be allowed to act. On the other hand, they were not being stealthy so Group B should at least be aware of them, too?
Would it be reasonable then for those hanging back to still act if they kept far away enough (but how far is far enough), or had terrain to hide behind (but wouldn't they still need to make stealth check to hide)?
Sorry if I'm over-analysing this. Just that this scenario has been on my mind the past few days, and my google-fu wasn't good enough to resolve this. So looking to you for advice. :)
Option 2 is correct. Each person in Group A makes their own Stealth roll, and each person in Group B makes their own Perception roll. Anyone in Group B who beats at least one Stealth roll gets to act in the surprise round, but they're only aware of the ones they see.
Having the stealthy ones advance while the clunky ones stay behind is a good tactic, because it's more likely that the stealthy ones will all get to act first. Anyone in Group A who has line-of-sight to anyone in Group B will need to make Stealth rolls, though-- so if they're hanging back far enough that Group B can't see them, that also means they can't see Group B and they aren't "aware" of Group B in any real sense. Only the ones that can see them get a surprise round.
Let's assume Group A1 is the stealthy half of Group A, and Group A2 is the clunky half. Group A1 decides to scout ahead so they can get the jump on Group B. Group A2 is so far back that they can't be seen, but they also can't see their enemies. Group A1 makes Stealth rolls and they're compared against Group B's Perception rolls. Then the surprise round happens between Group A1 and anyone in Group B that wasn't surprised. Then round 1 kicks in, and Group A2 can either make Stealth rolls of their own (they wouldn't get their own surprise round, but it could keep them from being seen at first) or simply charge in as normal.
Thanks for clarifying this.
Ok, so if Group A2 is not hanging very far back, but are behind trees or round a bend in dungeon passage so they can't be seen. Assuming that they are close enough to reasonably act in the surprise round. They then would need to make stealth checks to prevent Group B from being aware of them.
So if I can summarise it, anyone in Group A who wants to act in the surprise round must make stealth checks. Otherwise, they forgo the chance to act in the surprise round.
Don't forget the distance penalty for perception as well.
Ah, thanks. Forgot to check that. Hmm, see also a +10 to DC / foot of thickness. So if I was hiding behind a tree about 2 feet thick, that would be a +20 to DC, making the perception check almost definitely a fail?