So another question about surprise...

Scenario: My group makes a ruckus looking through barrels, and alerts the guards in the next room of intruders. The guards ready themselves by hiding on either side of the door. They have no stealth bonus. The group approaches the door and makes a perception check to listen to the other side, rolls a 20, so I say that they think they hear a quick shuffling and a faint "shhh" noise.

What happens next?

In my case, the group slowly and quietly opened the door without walking through it, and didn't see anything, so they stepped inside.

Can the guard swing his sword right away? Would it be a surprise round? Should I get them to roll initiative and maybe be able to dodge (move away from) the sword strike?

I want to make the game fluid and realistic, but don't want to bend and break rules all over the place. What should happen here, and how do other DM's carry out such a scenario?

Here is what I think happens, but I'd appreciate any input. Because both PCs and NPCs are on alert, there is no surprise round. Once the character walks into the room, combat "technically" starts and thus initiatives are rolled. If the PC outrolls the NPC, they can run backwards, or run past the guard further into the room. If the NPC wins initiative, it makes its attack on the PC. Correct?


There is no surprise here.

The guards are on alert. The PCs know there is someone on the other side (And presumably hostile). As Bradd points out, you want to make sure your guards to roll their stealth. Remember that skill bonuses are only listed for monsters if they're proficient. So use their Dex as their stealth check. Compare it to your PCs passive Wisdom (Perception) or they can roll it actively if they suspect someone is behind the door.

Basically, what happens is that the door is opened, and everyone rolls initiative. Initiative is the measure of how quickly you react when combat becomes inevitable. No one gets to jump that order.

I do not allow readying actions outside of combat (it's not explicitly prohibited, but its really not in the spirit of rolled initiative). Again, both sides are prepared, you go with initiative order.

One important note though. Don't start combat before the door is opened. Your PCs might realize they've been noticed and try to start a conversation through the door. This is a great opportunity for fun role playing and should not be missed.

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  • \$\begingroup\$ @BraddSzonye yeah, noted that in your answer, and included it here now too. Very good catch. \$\endgroup\$ – wax eagle Oct 10 '14 at 22:27
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    \$\begingroup\$ I didn't roll a stealth check in this case because the PCs rolled a natural 20 for perception and I ruled that they would hear something. Once they heard something, I figured they were on alert enough that they knew something was in there, and the guards wouldn't be able to hide from this sense. I guess the guards could have rolled a 20 stealth check though, and then yeah, could have surprised them. Their passive stealth is pretty low though, so I guess I decided to forgo it. \$\endgroup\$ – Besty Oct 10 '14 at 22:38
  • \$\begingroup\$ @Besty Yes, that’s a reasonable way to handle it. There’s another reason to roll the Dex (Stealth) check though: If the guards rolled very poorly then the PCs would have heard them via passive Wis (Perception) even without needing to roll themselves. I’ve added a note about it to my answer. \$\endgroup\$ – Bradd Szonye Oct 10 '14 at 23:06

There’s no surprise, but don’t skip the Dexterity (Stealth) check

The rules for surprise appear in the Basic Rules, p. 69:

The DM determines who might be surprised. If neither side tries to be stealthy, they automatically notice each other. Otherwise, the DM compares the Dexterity (Stealth) checks of anyone hiding with the passive Wisdom (Perception) score of each creature on the opposing side. Any character or monster that doesn’t notice a threat is surprised at the start of the encounter.

In your example, the guards are attempting an ambush, so you should first roll a Dexterity (Stealth) check for them and compare it to the players’ passive Wisdom (Perception) score. If the guards have no Dexterity bonus or Stealth proficiency, you still roll the check; you just don’t add anything to their d20 roll. This appears to be the only important step that you skipped. If the guards had rolled very poorly, then all the players would have heard them without even needing to roll a check themselves.

If the players also actively check for an ambush before opening the door, then they should make normal Wisdom (Perception) checks and compare them to the guards’ checks. They might hear the guards at that time even if the guards initially hid successfully. With a roll of 20, that would have been enough to notice the guards, given their low Dexterity (Stealth) score.

Anybody who “doesn’t notice a threat” will be surprised when the encounter starts:

If you’re surprised, you can’t move or take an action on your first turn of the combat, and you can’t take a reaction until that turn ends. A member of a group can be surprised even if the other members aren’t.

At least some of your players noticed the threat and communicated it to the rest of the group, and the guards were already aware of them, so nobody would be surprised in your example.

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    \$\begingroup\$ @Besty Roll as soon as you determine that the guards want to hide. You don’t need to tell the players why you’re rolling. If they roll poorly (below the PCs’ passive Perception) then you can immediately tell the players that they hear people moving in the next room. If the players get suspicious and ask for an active Wis (Perception) check, then let them roll. If they roll well, tell them what they hear. If they roll poorly, tell them they don’t hear anything out of the ordinary. \$\endgroup\$ – Bradd Szonye Oct 10 '14 at 23:35
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    \$\begingroup\$ @Besty Also, feel free to roll dice occasionally for no reason at all. That way, it will be less of a clue that something is wrong when you roll the dice for reals. \$\endgroup\$ – Bradd Szonye Oct 10 '14 at 23:36
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    \$\begingroup\$ I like the fake roll trick. I'll use that for sure. \$\endgroup\$ – Besty Oct 10 '14 at 23:49
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    \$\begingroup\$ You can also pre-roll for scenarios like this. Roll it during your session prep. \$\endgroup\$ – wax eagle Oct 11 '14 at 2:17
  • \$\begingroup\$ I've used a whole bank of pre-rolls before as a GM. It really sped things up when the unexpected inevitably happened! \$\endgroup\$ – Smithers Oct 12 '14 at 5:10

Nobody is surprised, because both parties are aware of each other. But D&D 5e has more tools than just surprise to model the various degrees of tactical awareness and preparation.

Ready: Though these ambushers haven't surprised the party, they ambushers are ready and waiting, so they probably have already taken a Ready action with a trigger like, "When someone walks through the door…" to make a specific attack. Especially competent ambushers can set up their Ready actions in a coordinated way for maximal alpha-strike effect.

Advantage: If in your good judgement you believe that the PCs have been especially careless in how they walk into the ambush, you can rule that the the PCs have given the advantage away to the ambushers and you can give the ambushers… (wait for it)… advantage! I would probably give this advantage on the Initiative roll, but if they're already Ready, giving it on the attack rolls would be appropriate and particularly nasty.

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    \$\begingroup\$ @BraddSzonye Speaking from experience, that's not actually a degenerate state. What happens then is that the rare correct predictions of combat-is-imminent are rewarded, and incorrect predictions are penalised (they just stand there for no reason when there's no danger, or failing some other check due to misdirected attention, etc). Like it would be in reality. From experience, it is actually the rigid separation of combat and non-combat time that actually leads to degenerate states... \$\endgroup\$ – SevenSidedDie Oct 11 '14 at 2:29
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    \$\begingroup\$ @BraddSzonye I use a method where being in-combat leads to virtually everything else being ignored (I cribbed it from Exalted), it basically boils down to a -10 to -20 being applied to a PC's checks for anything but the trigger to his readied action if he "readies up" outside of combat. If he called it right, of course, he gets first blow; otherwise, he may miss important stuff or be denied a check to not be surprised if it comes from someplace besides his trigger ("I attack the first person through this door!" "An archer shoots you through the window." "!@#$") \$\endgroup\$ – gatherer818 Oct 11 '14 at 6:57
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    \$\begingroup\$ @SevenSidedDie I don't like alpha strikes, I think they're detrimental to gameplay, and I'm not really swayed by “realism” arguments (partly because I don't trust them, partly because that's not why I play). So I guess we will need to agree to disagree. \$\endgroup\$ – Bradd Szonye Oct 11 '14 at 7:02
  • \$\begingroup\$ @BraddSzonye I suspect this is a Combat as War vs. Combat as Sport difference (which is irreconcilable, yeah). I prefer Combat as War, which isn't about "realism" so much as about fighting fair being a losing strategy. 5e is very well wired for Combat as War, and appears to default to it (especially in stealth and awareness systems like these). But it doesn't seem to hard-code it pervasively like AD&D does, so 5e can be pushed toward Combat as Sport mode if that's the DM's preference. \$\endgroup\$ – SevenSidedDie Oct 11 '14 at 7:09
  • \$\begingroup\$ Gatherer818's idea actually fits more of the active ambushes I've seen. \$\endgroup\$ – Smithers Oct 12 '14 at 5:13

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