As you enter the room, you see everything OR how to handle high passive perception

[Mentat55]

I've actually altered traps and hazards to have a Stealth check, instead of a Perception DC. When PCs first enter an area, I roll a d20 + trap's Perception DC -10, and compare it to the PCs' passive Perception scores.

I know the traps aren't actively hiding, but it is basically a way of moving the dice roll from the PCs to behind the DM screen.

 

[jtrowell]

Youn can also use the static passive perception versus DC system, but give a malus to perception because of distance (maybe -1 or -2 for each square) : that way if your high perception PC is behind its friends (bow ranger with high wisdom ?), he could still find the trap automatically, but maybe too late to prevent it.
This means too that another player having a good perception would not be wasted.

This can be used for ambushes too.

 

[keterys]

The second part of the arsludi article is particularly useful when it talks about a game in which the DM showed the party where all traps were in advance...

 

[DM_Blake]

I've actually altered traps and hazards to have a Stealth check, instead of a Perception DC. When PCs first enter an area, I roll a d20 + trap's Perception DC -10, and compare it to the PCs' passive Perception scores.

I know the traps aren't actively hiding, but it is basically a way of moving the dice roll from the PCs to behind the DM screen.

I like this approach.

It leaves a sense of danger in the player's minds. They know that at any moment they could plunge into a bottomless pit or get squished under a 10-ton falling brick.

They should also know their scout is excellent at spotting this stuff, and that scout should find nearly all the traps (assuming we're talking about the same highly-perceptive scout; they're in trouble if their scout has crummy perception).

So, the DM can now 'accidentally' roll occasionally so that a trap gets a chance to spring on the players - hopefully a trap that entertains as well as irritates the players.

Now, where'd I put that sphere of annhilation?

 

[DM_Blake]

Youn can also use the static passive perception versus DC system, but give a malus to perception because of distance (maybe -1 or -2 for each square) : that way if your high perception PC is behind its friends (bow ranger with high wisdom ?), he could still find the trap automatically, but maybe too late to prevent it.
This means too that another player having a good perception would not be wasted.

This can be used for ambushes too.

I don't remember seeing if 4e had rules for perception penalties over distance.

I know 3.5 had those rules.

Sometimes, it's nice to just chuck those rules out the window though.

For example, I think 3.5 rule said -1 to listen or spot for every 10 feet. So, theoretically, if you could spot a hair lying on a table directly in front of you with a DC 20 spot, then standing a hundred feet away means you could see that same hair with a DC 30 spot - which seems rather impossible to me.

It's very hard to see a hair lying on a table from more than a few feet away.

Given that many traps are cleverly concealed, only visible as hair-thin seams around a pressure point, or tiny pin-hole sized vents for expelling gas, it seems the same logic applies. If you are more than a few feet away from the visible signs of the trap, then it should be impossible to see.

Which falls in line with what jtrowell said. A ranger with great perception who is 5th in line of a group of adventurers will never see the seams of the pressure plate in time to keep the fighter (in front) from stepping on it.

Put the perceptive guy right behind that fighter, and he might be close enough, but now the fighter gives some cover to the trap, so we should consider modifying the perception roll according to cover rules.

At least, this seems to make sense to me.

 

[jedrious]

I don't remember seeing if 4e had rules for perception penalties over distance.

I know 3.5 had those rules.

Sometimes, it's nice to just chuck those rules out the window though.

For example, I think 3.5 rule said -1 to listen or spot for every 10 feet. So, theoretically, if you could spot a hair lying on a table directly in front of you with a DC 20 spot, then standing a hundred feet away means you could see that same hair with a DC 30 spot - which seems rather impossible to me.

It's very hard to see a hair lying on a table from more than a few feet away.

Given that many traps are cleverly concealed, only visible as hair-thin seams around a pressure point, or tiny pin-hole sized vents for expelling gas, it seems the same logic applies. If you are more than a few feet away from the visible signs of the trap, then it should be impossible to see.

Which falls in line with what jtrowell said. A ranger with great perception who is 5th in line of a group of adventurers will never see the seams of the pressure plate in time to keep the fighter (in front) from stepping on it.

Put the perceptive guy right behind that fighter, and he might be close enough, but now the fighter gives some cover to the trap, so we should consider modifying the perception roll according to cover rules.

At least, this seems to make sense to me.

If the target is more than 10 squares away from you the perception dc is 2 higher, it's in the tables in the PHB

 

[Stalker0]

You could always have the traps roll a stealth check vs passive perception. That way some traps might get through, and others even the lowly unwise warlord can see them.

 

[Wujin]

I don't remember seeing if 4e had rules for perception penalties over distance.

I know 3.5 had those rules.

Sometimes, it's nice to just chuck those rules out the window though.

For example, I think 3.5 rule said -1 to listen or spot for every 10 feet. So, theoretically, if you could spot a hair lying on a table directly in front of you with a DC 20 spot, then standing a hundred feet away means you could see that same hair with a DC 30 spot - which seems rather impossible to me.

It's very hard to see a hair lying on a table from more than a few feet away.

I am sorry to bother but you forgot the size modifier... a single hair should
have at least a +16 size modifier to his hide check and so the DC will
raise to 46 to spot it