Exploration, Stealth and transition to Encounter mode

[Lanathar]

Can people help me clarify the transition from exploration to encounter mode and how this works with Stealth

Say there is a party exploring.
And a monster is hiding.

What are the steps?

- Perception against Stealth DC.
- Initiative with monster rolling Stealth for initiative

How does this change if the party are also sneaking? Does the monster also roll perception against Stealth DC

And if the PCs fail the Stealth DC but roll higher Perception for initiative than the Monster's Stealth for initiative do they spot the creature? Or is that separate? Or can a monster only start hidden if the PCs both fail to spot it in Exploration and then it rolls higher Stealth initiative?

I am a bit confused

Question obviously reverses for the party. If they are trying to sneak around are they using static stealth DC or a rolled stealth score? And if a Perception based enemy initiative beats a stealth one are they seen? What if the perception beats the Stealth DC and not the Stealth initiative

This all occurred to me recently when my party were walking through the jungle and spotted a snake hiding near it's den. They decided to move away and I decided a snake wouldn't attack 4 people on it's own and left it at that

Is this clarified in the CRB and if so, what page? I don't have mine with me at the moment but still need to download my electronic humble bundle version so could cross check if there is a reference

[thewastedwalrus]

I've been running it as this:

- Stealthy creatures attempt secret Stealth checks against Perception DCs, failure means that they are noticed. They don't need to roll again until they decide to take the Sneak action to move up to half their speed from one point of cover/concealment to another or until they attempt to attack or otherwise start an encounter.

- A creature can take the Seek action and they get a secret Perception check against any hidden/undetected/unnoticed creatures in the area they are targeting. Success means they found the hidden creature while failure means they didn't find anything. If they search the wrong area then they get an automatic failure result.

- If either side want's to do something that will start an encounter, everyone rolls for initiative using the appropriate checks (Stealth for people being sneaky, Perception for the rest).

-- If the stealthy creatures roll higher than the Perception DCs of the rest, they begin combat undetected.

-- A creature in the perceptive group may still act first if they rolled higher but the sneaking creatures will still be hidden if they beat the perceptive creature's Perception DC. In this case the perceiving creature has noticed that something's going on but not exactly where the threat is.

[shroudb]

there was like a 300000pages thread back from the beta asking exactly what happens when both parties are stealthing, for all i know there hasnt been a concrete answer of how to resolve that.

so it boils down to however each group runs it.

for my table, i use "the movng party is the agressor" policy, so they are the ones that make the checks vs the static party DCs. If ALL agressor checks fail to detect any of the enemies, it switches to the static group rolling vs the DCs of the moving group.

It works fine because usually it's the PCs that are moving, so the players get to roll more dices.

[Xenocrat]

You can win initiative but fail to notice the enemy you've won initiative against, who has in turn noticed you. As a GM I'd then assume the PCs are doing what their exploration activity is during their "first" turn, then the enemy effectively goes first despite losing initiative. A backdoor surprise round in a way.

[thenobledrake]

Here's how this works by the book, and I'll include page references where I can:

First, the party is in Exploration Mode (p. 479) and has chosen their exploration activities (p. 479-480). Choice of activity will determine what each PC rolls for initiative (p. 468); for most activities it will be Perception, but any PC that was Avoiding Notice (p. 479) will roll Stealth (p. 468 and p. 479).

Second, what the creatures encountered are doing will determine what they roll for initiative for the same reason as it does the PCs, so an encounter with creatures laying in wait to attempt an ambush will roll Stealth for initiative as well.

Once the party enters the area in which the ambush is waiting, no matter what Exploration Activities they were doing, it's time to switch to Encounter Mode (p. 468) and roll Initiative (also p. 468) - because every individual action counts.

Anyone rolling Stealth for initiative uses that one roll both as their initiative result, and compares it to the Perception DC of their enemies to determine if they start the encounter unnoticed or not (p. 479) - assuming, of course, that the encounter area has appropriate cover or concealment to allow for not being observed (the Hide (p. 251) and Sneak (p. 252) actions cover this)

As turns play out, the PC will be taking a lot of Hide, Sneak, and Step actions to keep from being detected, and should also probably through in some Seek (p. 471) actions to try and see any enemies, hazards, or other things they might be interested in before those things catch them off guard. And the enemies trying to ambush passersby will mostly take Seek actions until they manage to spot some one to spring the ambush on.

If the encounter goes just so, the party may pass through the area and move on without the enemies having noticed them and without the PCs knowing they'd just dodged an ambush.

For the sake of this kind of encounter not feeling "rigged" to the players, I'd recommend the GM determine either a pattern for the seek actions taken by each enemy along the lines of "cone right, cone left, burst at [specific point on map]" or randomly determine what area each monster is seeking in with each Seek action so that the players might simply never be in the area of a Seek action if they move to the right places at the right time - because the enemy always picking the right spot to potentially find a character is like when a fighting game CPU character is programed to do whatever would defeat or negate the button the player just pushed.

[Captain Morgan]

Initiative and Stealth
Source Gamemastery Guide pg. 11
When one or both sides of an impending battle are being stealthy, you’ll need to deal with the impacts of Stealth on the start of the encounter. Anyone who’s Avoiding Notice should attempt a Stealth check for their initiative. All the normal bonuses and penalties apply, including any bonus for having cover. You can give them the option to roll Perception instead, but if they do they forsake their Stealth and are definitely going to be detected.

To determine whether someone is undetected by other participants in the encounter, you still compare their Stealth check for initiative to the Perception DC of their enemies. They’re undetected by anyone whose DC they meet or exceed. So what do you do if someone rolls better than everyone else on initiative, but all their foes beat their Perception DC? Well, all the enemies are undetected, but not unnoticed. That means the participant who rolled high still knows someone is around, and can start moving about, Seeking, and otherwise preparing to fight. The characters Avoiding Notice still have a significant advantage, since that character needs to spend actions and attempt additional checks in order to find them. What if both sides are sneaking about? They might just sneak past each other entirely, or they might suddenly run into one another if they’re heading into the same location.