Monsters using stealth

[deleteme123456]

You could say that, but it would be a house rule, and one that turns the Stealth ruleset on its ear as it deviates very widely from RAW. Again, the Take 20 option, as you're calling it, is not available to PCs; it's a tool the DM can use to speed up play for repeating the same skill check when there is no time constraint (DMG p.41). The shortcut is there to avoid wasting the group's time by repeating the same skill check when there would eventually be a success anyway. The example given is searching an empty room after the encounter has been dealt with and there is no chance that more monsters will show up while the party is searching. The DM handwaves the series of rolls and assumes that a 20 will eventually be rolled and is told to

Take 20 as it existed in 3.x does not exist in 4E. The way Perception checks are made in your ambush scenario are described under the Perception skill in the PHB: you either make a passive check for the players (Take 10) or the players make an active check (they roll d20).

When on the alert for danger, as your party is, they make an active check: no Take 20 allowed. There was a thread here on ENWorld (a few months old now I would say) that discussed the odd situation of an active Perception check yielding a lower result than a passive check. The consensus was that a Stealth check had to beat both a passive and active Perception roll, if an active check was made, but I don't know if the basis for that was somewhere in the DMG/PHB, a Wizards employee clarification, or was just a common sense thing. I don't see it in the updates...

Scenario: PCs have been sent to eliminate a Kobold threat in the area. They have good intelligence (as in CIA, not as in INT) as to where the base is, and they approach cautiously, looking carefully for hidden Kobolds. You really don't think this qualifies as take 20?

How about this then: the best perception player in the group asks up to 4 friends to aid him... since no one has a negative WIS mod, they all choose to take 10 on this check to aid another, and then the point man chooses to take 10, so he gets percp + 18, which is going to beat most stealth rolls the Kobolds can come up with (not all maybe, but most, really depends on what base perc is, if we're working from +6 or +9, etc.).

 

[the Jester]

You really don't think this qualifies as take 20?

There is no 'take 20' per se in 4e.

Even if there were, there is a penalty for failure, so I wouldn't allow it.

 

[deleteme123456]

There is no 'take 20' per se in 4e.

Even if there were, there is a penalty for failure, so I wouldn't allow it.

From one of my PCs who isn't just trying to be difficult (because usually I tell them no, when someone else is telling me no, I know something's up, so I asked for his opinion as a rules lawyer). He argues that take 20 perception is a fair abstraction of this:

Dwarf (move action: 5 squares (25') / 6 seconds) --> 250ft/min, or ~3 mph. (A reasonable hiking pace.) DM's note: this is also the approximate overland speed given elsewhere.

Figure that the standard action --> minor action. The characters (being bored/alert/suspicious), do two perception checks per move. You now have 5 characters rolling twice per round. Even with penalties for noise (e.g. the dwarf's armor), it's awfully tough to survive 10 rolls against perception for multiple creatures.

With a very good roll, a single stealthy character (myself DM note: Rogue at +9) might be able to clear, say, 25, and dodge perception checks, especially with modifiers for a good hiding place (e.g. not strictly ambushing, but perhaps just observing), noise, etc. I'd still have trouble against a disciplined group paying attention, although I might be able to shadow, say, a band noisy orcs after their day of looting.

But for any sizable group (N=3+), the odds of all characters rolling stealth (1d20+mod > 20) is pretty slim, and take 10 + modifier ~= 20. Now assume only the perception characters (3 of the party) are at +6, and we look twice per round: 82% of the time, one of six rolls is at least a 16, giving us 22. By the next round, the odds are 3% that we haven't rolled a 16+.

 

[OchreJelly]

In regards to what the kobolds could do with their stealth besides remain hidden or use ranged weapons, how about charge!

Really this is a good choice for any stealth monster that has a 'combat advantage' ability but no good power that contains movement and attack rolled into one.

 

[MarkB]

From one of my PCs who isn't just trying to be difficult (because usually I tell them no, when someone else is telling me no, I know something's up, so I asked for his opinion as a rules lawyer). He argues that take 20 perception is a fair abstraction of this:

Perception checks as a minor action show up only in one place in the PHB - checks to determine the position of an invisible creature whose presence you are aware of. For all other purposes, you use the rules under the Perception skill description, which make an active check anything from a standard action (most appropriate for making active checks to spot hidden creatures) to a full minute (most appropriate when searching for traps or secret doors). And just personally, even as a minor action I wouldn't allow multiple active checks per round.

That limits the party to one active check per round per player, only 50% of which will even beat their passive Perception. And unless the ambushers are particularly dim, they'll choose positions which grant them total cover until their opponents are as close as possible to the optimum ambush position, so the party won't have more than a couple of rounds in which to succeed at their Perception checks.

Finally, the whole point of passive Perception is that it represents the normal state of alertness of a group of creatures in potentially hostile territory, so that the DM can use it instead of calling for active checks every five minutes. Active checks are what you make when you're aware of a specific threat and trying to find it. Don't let your players bully you into letting them effectively make their active checks passively with this "take 20" argument - it's not the way the game is built to work.

 

[Josep]

That limits the party to one active check per round per player, only 50% of which will even beat their passive Perception. And unless the ambushers are particularly dim, they'll choose positions which grant them total cover until their opponents are as close as possible to the optimum ambush position, so the party won't have more than a couple of rounds in which to succeed at their Perception checks.

So we have three kobolds lying in wait with a stealth check of 20. (e.g. take 10 + kobold modifiers). The perception DC for spotting creatures is +2 for anything over 10 squares. The characters suspect kobolds lying in wait, so they are using standard actions to do spot checks. Assume no detection possible over 20 squares, and the characters are moving 5 squares / round (call it 4 checks at 17, 12, 7, 2 squares).

So the characters get 10 checks against DC 22, and another 10 checks against DC 20. Given three PCs (as described) at +6 perception, assume another +2 and the last one at +0.

At distance 17 / 12 (DC=22): Three PCs 'spot' the kobolds on a 16 or better, the fourth on a 20, and the last one not at all. Odds per round of spotting the kobolds: (1-0.75*0.75*0.75*0.95)=60%. Odds over two rounds: 86%.

 

[Ulorian - Agent of Chaos]

Perception checks as a minor action show up only in one place in the PHB - checks to determine the position of an invisible creature whose presence you are aware of. For all other purposes, you use the rules under the Perception skill description, which make an active check anything from a standard action

The PHB update has changed the Perception check to a minor action from a standard action.

 

[MarkB]

The PHB update has changed the Perception check to a minor action from a standard action.

Well, at least that clears up the discrepancy between the Perception skill and the Finding Hidden Creatures rules. I'd still tend to only allow one per round, though.