How do I use passive insight checks?

Question

On page 26 of the DMG, it describes a passive insight check and gives an example of using it in a social encounter. Could you help me with it and how to use it? Step by step would be appreciated

Answer 1

The passive insight check is not something that is rolled or actively used. It is more like armor class or a reflex defense, a number which the opponent must beat to successfully deceive the character. As such, there is no retrying, just as there is no retrying an armor class or reflex defense.

It is, from a gameplay perspective, a tool to speed up the game and reduce randomness. It's basically the assumption that a character takes 10 on their insight checks on these situations. Beyond that, it assists the DM because calling for insight checks is a sure way to make the PCs realize something is up.

It's the same deal with passive perception, except that's used to stealth rather than deception.

Answer 2

From a GMs perspective:

Passive insight is the DC for any subterfuge (bluff & intimidate) checks made against the PC.

It is the PC's defense against social attacks. Much the way AC is the defense against weapon attacks.

If your NPC is trying to lie to a PC, you roll a Bluff of your NPC against the PC's passive insight. If your bluff does not exceed the PC's insight, you should hint to the PC that something the NPC just said does not sound right.

Answer 3

Generally I would have the players passive insights in front of me and if one of them would automatically be able to tell if somebody was acting oddly or lying, then I would give those players a little extra information.

For example, the basic description: "As you approach, a figure comes up to the bars of the cage and pleads with you to let him free. The figure is a female elf, dressed in tattered rags, and seems to have been beaten."

If a player had a very high passive insight, I might tell that player the additional: "The way in which the figure moves appears unnatural, as if the elf is not comfortable with its body"

I wouldn't have somebody "use" their passive insight. It's more a tool for me to determine how much information to give out without the character making an active check.

Answer 4

You've missed a key element in a "passive insight" check — they aren't rolled. You compare the character's Passive Insight score to the difficulty of the check, and determine whether they succeed or not based on that. Applying a penalty wouldn't have any effect at all; future "checks" would still fail, only by a greater amount.

Now, you could apply a small bonus if you chose, reflecting greater exposure to the stimulus. But, at that point, you'd be better off rolling.

Answer 5

One of the game design goal of things like passive insight (and passive perception) is to allow the DM to adjudicate scenarios where knowledge of the insight (or perception) test would grant the players knowledge that their characters should not.

Imagine a scenario where the characters are approached by an NPC with a story of woe, that in actual fact is a fabrication to try and lure the characters into a trap.

The NPC needs to make a bluff check, but if, as the DM you call for an insight check to oppose the bluff role, you tip your hand to the players that there is something for their characters to discern.

Enter the passive insight score.

• If the NPC's bluff is lower than one of the players passive insight, you can clue them in that something might be afoot by telling them that something doesn't ring true ... with the expectation that they will now try rolling insight.
• If the NPC's bluff is higher than everyone in the parties passive insight, none of the characters note anything unusual, though a suspicious player may think to try to roll insight.

As other answers have noted, in order to make this flow most naturally, as the DM you'll want to know the passive insight of your players in advance, and thus avoid having to break out of role play to ask for their characters' stats.