After having last played Basic D&D when I was 11, I'm having a great time playing Pathfinder with my own 11 year-old son. We tried the Dungeons & Dragons Starter Set over the Christmas break, but some research led me to propose getting into Pathfinder instead of 4e. One of the issues is the availability of the products in French; we live in France and, though we've only used the English language products so far, any friends of his that join us are more likely to be comfortable in French than in English. The newer 4e products aren't being translated, whereas the translator for Pathfinder here does seem to be keeping up.
Anyway, we just finished "Masters of the Fallen Fortress" with him controlling two characters and me GM'ing, handling two others, and generally providing tactical advice. A good time was had by all, but one thing I'm still wondering about is the general course of events for bursting into a room with bad guys. The party rogue checks for traps, sees if the door is locked, attempts to pick the lock, and then opens the door. If that doesn't work, the ranger kicks in the door :).
At that point, how does surprise work? Are the monsters within tipped off by the attempts to open the door? In retrospect, a perception check for them would make sense. How about if the door is kicked in in one try? I could see ruling either that the monsters are alerted by the noise, or that they are totally surprised by the brutal entrance.
I ended up not running any surprise rounds, but I'm wondering about how to do this "properly."
The situation is a little difficult. I think there's a lot of little (and big) ways to run it, but I can show you what might happen in my game.
The first questions I'd ask is, who is stealthing? If you want to do it quick and dirty, you could just say that people not attempting to stealth are immediately detectable. This situation can become about as complex as you allow it to, so it may be to the taste of your group that people not trying to be stealth won't be undetected. So, if you want to make it complex ...
Determining if the players are detected
Hearing footsteps is normally Perception DC 10.
[You might apply situational modifiers -- it doesn't make sense to some GMs that a fighter with full platemail and a tower shield (armor check penalty of -16) might Stealth, roll 20, and it turns out he is much harder to hear while walking normally than while making the best Stealth check he could ever make, which is a 4.
It might also make sense to apply the size bonuses / penalties to stealth from this. It makes sense that the footsteps of a giant are easier to hear than a human's, and a cat is harder to hear.]
Listening through a door is +5 to the DC of Perception checks, then Perception DCs are at a +1 penalty for every 10 feet of distance between the source and listener.
So if your players don't stealth as they approach the door, there's a chance that creatures inside might be able to hear their approach. Suppose that two creatures are inside a room, with 15 feet between them and the door; the players approach up to the door. The players create the noise of footsteps (DC 10), heard through a door (+5), and the opponents are 20 feet away from the closest sources of sounds (+2). So it seems that the creatures inside would be able to hear the player in front with a DC 17 check, and most of the rest of the party an equal or or similar DCs. [If you apply armor check penalties to this check, it's almost impossible for creatures not to notice a character in platemail -- which is realistic, in my opinion.]
I want to move on to determining if creatures are detected, but I'm running into some strange cases and my time is running out, so I'll save it for later or the next poster that's brave enough to tackle a controversial issue.
simple answer: surprise happens when the mobs know there is someone there. (same as with a surprise party)
assuming they mobs are not asleep (is like a -10/-20 to the check, i cant remember which), they would be surprised by the door being slammed in, or the first person charging in.
i would say:
on slamming the door open, and the mobs being ready (armed, etc) the surprise round would consist of the kicker (maybe...more on that in a sec) and possibly people before goblins in init...
why maybe kicker, i'd assume was standard to kick door...
with charging in, i'd say the PC's would get surprise, fully...
if they were partially detected, some mobs and some pc's would act
and if they were detected, maybe the goblins hid under the beds (stealth vs perc) and then charge out and THEY get a surprise round
Checking for traps probably doesnt make any noise, disabling a trap or picking a lock would make some faint sound, i'd called it a dc 20 perception check to hear that on the other side of the door, but i would allow the rogue to make a stealth check instead if he wants.
As for the kicking down the door, that definately alerts the enemies. They would not be surprised, and everyone would just roll for initiative and act. Only if one side or the other is actually being stealthy (all members getting into the conflict) do you have surprise rounds.
What should the base DC be for detecting a creature in the next room? I know a door should add +5, but now I'm second-guessing myself regarding what to add it to. (Assume the creatures aren't stealthing -- they're leaning against the wall, or sleeping, or quietly playing cards.)
I wanted to use the 'creature is visible' DC and just modify the DC for the door and distance, but then I realized that would make it easier to hear a creature standing on the other side of the door than a creature that's walking around on the other side of a door. That's a bit backwards.
sounds like dc 10 base 'sound of a creature walking'
+5 door
+1/10'
+5/10 (distracted or asleep)
[+2/-2/-5] random modifier (echoing caves, etc)
That depends. If you kick in the door in one move and rush in? Surprise definitely seems plausible. If you have hit it multiple times to get it down? Not so much.