Stealth & Perception

[chaotix42]

OK, I think I have the rules for hiding all sorted out. Someone step in here if they think I've got something wrong.

First, we have the rules for making "Checks without Rolls" on pg. 179 of the PHB. This states that "in a calm environment (outside an encounter), when dealing with a mundane task, you can rely on sheer ability to achieve results." It goes on to then describe Taking 10 and Passive checks.

- Outside of combat or other encounters your DM usually uses the PC's passive Perception checks. Monsters sneaking up to ambush the PCs make Stealth checks vs. the PC's passive Perception checks, for example.

- If a monster (or monsters) fails to beat a PC's Passive perception then they may be spotted:

a) If all they have is concealment or cover to a PC they can see the monster.

b) If the monster has total concealment or superior cover to a PC he instead knows the direction to the monster and has a vague idea of the distance to their square; if the passive Perception check beats the Stealth check by 10 or more the PC pinpoints the monster's square.

So, a few monsters roll poorly on their Stealth checks, starting an encounter.

- In combat the monsters are moving around, taking their attacks and using Stealth whenever possible. Now that we're in an encounter the PCs stop using their passive Perception checks and can begin rolling their Perception checks when an Opposed Check is called for (as per the "Opposed Checks" and "Checks without Rolls" rules on pgs. 178 and 179 of the PHB).

- When a monster makes a Stealth check it can roll Stealth as part of whatever action it is trying to perform stealthily. Most monsters cannot attack and remain hidden while doing so, so often an attack will be followed by a retreat into concealment or cover, allowing a Stealth check with the appropriate modifiers. At this point all observers get a chance to spot the monster depending on whether the monster has concealment/cover or total concealment:

a) If the monster only has concealment/cover to an observer it can still be seen - the opposed Perception check is rolled with no action required. Those that beat the monster's Stealth check can see it and attack it normally, with the standard penalties for attacking obscured targets. Those that do not beat the monster's Stealth check cannot see their target and must use the "Targeting What You Can't See" sidebar on pg. 281

b) If the monster has total concealment to a target, you can't see the target. If you can't see the target you use the "Targeting What You Can't See" sidebar on pg. 281. At this point the opposed check is the monster's Stealth check vs. the observer's passive Perception check, despite the "Checks without Rolls" rules on pg. 179. If the passive Perception check beats the Stealth check the observer knows the direction to where the monster ended its move, and if it beats it by 10 the observer knows what square the monster ended its move in. If the observer needs to, on their turn they can roll an active Perception as a minor action to try their hand at the whole process once again.

There is a bit more to it but these are the basics. The way that Stealth and Perception interact with one another is poorly explained and at times contradictory but I think I've got it right. Any objections?

 

[Surgoshan]

I think it would be clearer if you changed a bit on total concealment during combat.

this is because you cannot actively perceive what you cannot see.

You can actively perceive it, in fact that's what a perception check is. However, because of the total concealment or superior cover, you can't do it as a free action. In other words, you can't just glance around to see your opponent. You have to stop and look/listen carefully, thus making it a minor action.

I'm assuming, though, that this is part of combat and we're talking about a creature that has attacked and, as part of its move action, retreated into superior cover/total concealment.

If the opponent is unaware of the hiding creature, then the creature makes an opposed Stealth check against the unaware opponent's Passive Perception. The unaware creature can also make a Perception check as a standard action at any time. If the Stealth check fails either of those opposed checks:

A1) No Cover/No Concealment: Creature is seen.
B1) Cover/Concealment: creature is seen, can now be attacked with -2.
C1) Superior Cover/Total Concealment/Invisible: The creature has been pinpointed and can be attacked at -5.

I would put it this way, for a stealth check made during battle*;
A2) No Cover/Not Concealed/Not Invisible: Not hidden.
B2) Cover/Concealment: Stealther must make an stealth check. Failure means the creature has been spotted and can be attacked with a -2 penalty. Success means the stealthy creature is hidden and the opponent has to guess which square to attack and does so with a -5 penalty. The perceiver can make a new Perception check on his turn as a minor action.
C2) Superior Cover/Total Concealment/Creature Invisible: Opposed stealth check.
C2)i] The Stealth roll beats the Perception roll: the hiding creature is succesfully hidden, the perceiving creature knows nothing of its location. Any attacks are made at squares at -5 and are complete guesses. The perceiving creature may attempt a new Perception check against the hider's last roll as a minor action.
C2)ii] The Perception roll beats the Stealth roll by less than 10: The perceiving creature knows the hiding creatures general area and direction. The perceiving creature must still guess which square the hiding creature is in and attack at -5. The perceiving creature may attempt a new Perception check against the hider's last roll as a minor action.
C2)iii] The Perception roll beats the Stealth roll by 10 or more: The hiding creature has been pinpointed and the perceiving creature can attack his exact square with a -5 penalty. The perceiving creature may attempt a new Perception check against the hider's last roll as a minor action... but why the hell would he want to?

* The first trio of options is a check made against a creature unaware of the hiding creature. The result of failure is the beginning of some kind of encounter.

 

[chaotix42]

I think it would be clearer if you changed a bit on total concealment during combat.

You can actively perceive it, in fact that's what a perception check is. However, because of the total concealment or superior cover, you can't do it as a free action. In other words, you can't just glance around to see your opponent. You have to stop and look/listen carefully, thus making it a minor action.

Good point. You get a minor action to actively perceive what you can't see. I edited the post to remove that little comment. : P

I would put it this way, for a stealth check made during battle*;
A2) No Cover/Not Concealed/Not Invisible: Not hidden.
B2) Cover/Concealment: must make a stealth check. The opponent then must use a minor action to make a perception check against the stealth score and can see the creature attempting to hide. Success means the stealthy creature is seen and can be attacked at -2. Failure means the opponent has to guess which square to attack and does so with a -5 penalty.

If someone with only concealment or cover makes a Stealth check in combat shouldn't observers get an opposed check for free?

 

[Vikingkingq]

Question: what counts as cover and what counts as concealment inside and outside of combat? I've never been too clear on this, and would like to get better at using stealth.

 

[Eldorian]

You get a minor action to actively perceive what you can't see.

Where do you get that? I see standard action to perceive under the perception skill.

 

[chaotix42]

Check pg. 281 of the PHB.

 

[Eldorian]

Check pg. 281 of the PHB.

Damn. That directly contradicts page 186, on the perception skill. I guess the combat chapter is the exception, which makes it a minor action to spot stealthy characters in combat.

 

[Surgoshan]

If someone with only concealment or cover makes a Stealth check in combat shouldn't observers get an opposed check for free?

Yep. I'm editing to change it. It's an opposed check. If the perceiver fails, he can try again on his turn as a minor action.

 

[Morgoth the Pure]

Bluff

I'm curious on your interpretation of the 'Create a Diversion to Hide' use of the Bluff skill. It's not clear to me how that works. It says you can use that skill once per combat encounter to allow a character to hide without the need for cover or concealment. If you succeed, you can immediately make a Stealth check to hide. But how long does the diversion last? I'm tempted to rule it lasts until the end of the creature's next turn (giving the character some time to reach cover), or until the character takes an action that would otherwise break stealth, such as an attack.

Any opinions?