Question about Stealth

[MDCityNIGHT]

In the Core Rulebook, it stated that "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 concealment." Is the Stealth check and Perception check made when they are first able to sense the rogue? Is it an every round check? I am confused as to when you need to make the check.

[aboniks]

I have seen stealth treated different ways by different DMs.

As I understand the rules, they state that it should work like this:

In concealment, or when unobserved: Stealth check once. Treat the roll on this check as the number that anyone who would have a chance to Perceive you will have to beat from this point on, until you perform an action or conditions change (ie. someone lights a torch near you, you start moving at a different speed, you step on a cat). If you are moving at full speed when they get to roll to perceive you, treat your stealth roll as if it were -5. Until you do something that alerts someone to your presence, or until a new opponent comes into line of sight/hearing/sniffing, you continue to use your original stealth roll as the number to beat to perceive you. Each person you're attempting to hide from only gets one perception check until there is a specific reason for them to re-roll.

Example:

You're sneaking up on a guard who has no line of sight, at night. Roll stealth. Let's say your roll plus your stealth skill equals 25. Approach him at half speed or less. When you come into line of sight, he rolls to perceive you, trying to roll 26 or higher. He fails. You keep Sneaking up on him, moving at half speed, using your initial roll (25).

You see that he's pulling out a lantern and a tindertwig, and you're too far away to get to him before he lights it. You decide to run at him. The guard re-rolls his perception check against your original stealth roll, minus 5 because you have started running (20). He rolls a 21. Your stealth is blown, he's aware of you.

Alternatively, when you start to run at him, say he rolls a 20. He hasn't beat your stealth. He's still unaware. As you move into position to sneak attack him, you enter the line of sight of a second guard. You're still running. The second guard makes a Perception check to beat your running-adjusted stealth score of 20. He fails, and is unaware of you.

You're now in position to sneak attack the first guard. You choose to do so. Everybody involved rolls initiative. Lets say your roll is better than either guard. You will be attacking in the surprise round.

You are still in line of sight for the second guard when you attack. You sneak attack the first guard and he dies. Attacking means you have broken stealth. The second guard is now aware of you. Surprise round ends.

(Up to this point you have rolled stealth only once, and three perception checks have been made against your roll.)

Next turn, you want to escape the second guard and hide. You take a move action to get either A) out of his line of sight, or B) into concealment or cover, (ie. into an area of darkness, behind a crate, etc.). Stealth can be used as a move action, so you use the rest of your turn (second move action) to make another stealth check. You roll a 15. Turn ends.

Next turn, there's nowhere for you to move to that doesn't put you in line of sight. You ready an action to sneak attack him if he gets close enough. He has a general idea of which way you went, but he's cautious and doesn't get close enough to attack. He moves to a position that gives him line of sight on your last known location. If that gives him line of sight on your current location, he rolls Perception to beat your 15. He rolls a 10, and fails. He still knows generally where you were last, so he moves towards that location. Turn ends.

Next turn, hear more guards arriving in the area. You drink a potion of invisibility. This is an action that could be perceived by the guard, who still has line of sight. You roll a new stealth check. It's 20. (Invisibility is a +20 stealth bonus while moving at any speed, or +40 if you stand still.) The guard rolls perception to notice you drinking the potion. He has to beat a 40. He fails. You know the guard is getting close enough to bump into you on his next action and become aware of you that way unless you move. You decide to move away, and escape him. You move at half speed, creeping along, until you are out of line of his line of sight.

You mend your devious ways, and the next day you renounce your life as a rogue and become a monk instead. Good call. I like monks.

Hope this helps. Except for that last bit, obviously.

[Drakkonys]

Stealth checks are opposed to Perception checks of anyone who might notice you. That means that every time you roll a Stealth check, anyone who might notice you rolls a Perception check. When making an opposed skill check, the attempt is successful if your check result exceeds the result of the target.

[Claxon]

Right, and anytime the conditions or modifiers change they should get a new roll, but the Devs clarified that within a single turn you should just roll once at whatever point is most favorable for the creature attempting to detect the creature attempting to hide. This reduces the number of rolls instead of worrying about every 10ft the character moves away or toward a creature (and you are applying the distance penalty for perception aren't you?).