Surprise is one of D&D’s most commonly misunderstood mechanics.
Newer players and DMs alike often don’t have a clear idea of how surprise works – of what it does and what it doesn’t allow.
How does surprise work?
D&D Basic Rules, p72
“A band of adventurers sneaks up on a bandit camp, springing from the trees to attack them. A gelatinous cube glides down a dungeon passage, unnoticed by the adventurers until the cube engulfs one of them. In these situations, one side of the battle gains surprise over the other.
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.
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 re-action until that turn ends. A member of a group can be surprised even if the other members aren’t.”
The rules for surprise are very straightforward, especially considering how much confusion they cause. There are some important nuances that you need to be aware of though.
When a combat encounter begins, before any turns are taken and before any attacks are made, the DM determines where all combatants are positioned and whether any of them are surprised.
A combatant is surprised if they weren’t aware of any threats before the start of combat.
Once these two things have been determined, the DM calls for an initiative roll. All combatants roll initiative, including any who are surprised.
Surprised combatants can’t move or take any actions until the end of their first turn in combat. They can take reactions during the first round, but only after their first turn has ended.
After the first round of combat, the effects of surprise end, and all combatants continue in normal initiative order.
How does the DM determine surprise?
Surprise only comes into effect if at least one side tried to attack stealthily. If neither side tried to be stealthy then both sides automatically notice each other and no one is surprised.
If the attackers did try to engage stealthily then all characters from the attacking side roll stealth checks against the passive perception scores of the defenders.
If a character from the defending side detected any characters from the attacking side, then that character isn’t surprised. This is still true if they only detected one out of several attackers. In this case, that character takes their turn in combat normally.
If a character from the defending side detected none of the attacking characters, only then are they surprised.
Surprise is determined separately for each character so some defenders may be surprised and some may not be.
If a defender notices any threats at all then they’re not surprised. That said, if a defender hasn’t noticed one specific attacker, then that attacker still gains the benefits of being an Unseen Attacker when attacking that defender.
That means that defender won’t know the attacker’s location and the attacker will gain advantage when attacking that defender.
This is only true of the attacker’s first attack though because, regardless of whether it hits, making an attack gives away your presence and location.
Surprise and Reactions
One common misunderstanding about Surprise is the belief that a Surprised creature cannot act for the entire first round of combat. This isn’t the case!
A surprised creature can’t take reactions until the end of its turn. As soon as its turn ends though, it can use its reaction.
That means it can take opportunity attacks, or cast reaction spells like Counterspell, during the first round of combat. If the creature rolled well on its initiative then it may be able to take reactions before most of the party have acted!
I’ve heard people talk about a “Surprise Round”…what is that?
“Surprise Round” is a hold-over term from D&D 3.5E. The mechanics of Surprise worked slightly differently in 3.5E and were resolved through a Surprise Round at the start of combat.
The term “Surprise Round” isn’t used in D&D 5E and Surprised is treated more similarly to Conditions like Prone or Restrained.
The results of this are quite similar but not identical. The term “Surprise Round” is still used by some 5E players and this can sometimes cause confusion.
The word “Round” implies that Surprised creatures can’t act at all for the first round of combat but they can actually take reactions.
“I cast Fireball at the shopkeeper” – Surprise when transitioning from roleplay to combat.
In every lighthearted hack & slash D&D campaign, a situation will eventually arise where the party suddenly attack an NPC they were just conversing with.
Maybe the party doesn’t like a shopkeeper’s prices. Maybe they don’t like a guard’s attitude. Maybe they’re just bored of roleplaying and want to smash something.
Whatever their motives, a player announces their attack against an NPC who wasn’t, until that moment, hostile.
Often the DM can feel pressured, in these situations, to make one of two rulings:
The DM might allow the aggressing player to fully resolve that initial attack they’ve declared before combat starts and before initiative is rolled.
This feels natural because you’re in roleplay mode where turn order doesn’t exist and players can announce what they intend to do and then immediately do it.
And if the player’s attack is what begins combat, surely it would be ridiculous if other combatants were to act before them?
Alternatively, the DM will rule that the NPC is surprised and allow the entire party to take their turns before the NPC can act at all.
As a newer DM making rulings on the fly, it might even feel tempting to allow both. This allows the aggressing player to take two or three attacks (depending on initiative order) before the NPC can even act.
None of this is within D&D’s rules for surprise. The NPC was fully aware of the PC who attempted to attack and therefore wasn’t surprised.
If a player draws their weapon or begins casting a spell with verbal, somatic, or material components then the NPC would view them as a threat.
If a player sucker-punches the NPC or casts a spell without verbal, somatic, or material components then it makes sense that the NPC wouldn’t previously have viewed the player as a threat.
The player should make a deception check, contested by the NPC’s insight. If the player succeeds then NPC should be surprised but so should the rest of the aggressing player’s party!
A player can announce that they intend to attack but their attack still isn’t resolved until their turn. The NPC may even get to act before them!
To make this feel more natural, you can roleplay the NPC as noticing that a fighter is drawing his sword or that there are sparks of flame coalescing in a wizard’s hand.
If your player wants to play a casts-from-the-hip outlaw spell-slinger with the fastest fireballs in the west then, rather than bending the rules, you should suggest that they take the Alert feat or put some extra points into dexterity.
Both of these things will allow them to act earlier in combat.
Attacking friendly NPCs unprovoked can sometimes become disruptive so it’s best not to mechanically reward the player responsible by allowing them extra attacks.
What happens if one player attempts to distract the NPCs, allowing the rest of the party to attempt a sneak attack?
This is a case where the rule books don’t provide a complete answer. If the distracting player is successful then this should mean that they’re not perceived as a threat by the NPC.
Their actions should also make it more likely that their party succeeds in making a sneak attack.
Within the rules, I’d interpret that the distracting player can make either a deception or performance check as determined by the DM. This is contested by the NPC’s insight.
If the player succeeds on this check then the NPC has disadvantage against the party’s stealth checks. Disadvantage on passive perception is processed as a -5 bonus (see p177 of the Player’s Handbook), so the NPC’s passive perception is decreased by 5 when determining whether the party’s stealth checks are successful.
If the rest of the party succeeds on their stealth checks then the NPC is surprised. These interpretations are all well-grounded in the rules, although the rules could be interpreted differently.
Where this gets complicated is in determining whether and when the distracting player gets to attack.
There are a few different rulings you could make here.
The distracting player could have used their turn to distract. In this case, they wouldn’t get another turn during the first round but they would be able to take reactions.
The distracting player could be allowed to take their turn normally. This feels unsatisfactory for two reasons.
First, there’s no trade-off in distracting the NPC. Nothing has been sacrificed to gain an advantage when making the stealth checks.
Second, the distracting player could roll well on their initiative and attack before their party members’ sneak attack has even been made.
As a third option, the distracting player could be automatically relegated to going last in the initiative order. This feels inelegant and is probably the least likely ruling that the game designers would intend.
In my game, I use the first of these rulings. This is an area where the rules are open to your interpretation as a DM though.
Can player characters be surprised?
Absolutely! This is one of the major risks you take in building a character with a low passive perception score – it means enemies are more likely to take you by surprise.
If you’re a DM then it’s good to take note that enemies sneaking up on your players will roll against their passive perception score to determine their success.
This means your players won’t be aware of the danger until multiple dice rolls have already been made against them and the success or failure of the initial sneak attack has already been determined.
Some players enjoy preparing to better counter these sneak attacks but, if your players prefer to jump straight into the action, then they might feel like there’s not much counterplay to be had. This can become frustrating for players.
There are ways for players to avoid being Surprised by enemies though.
How To Avoid Being Surprised
Playing a character with high wisdom and proficiency in perception will mean your passive perception score is very high.
Since enemies roll against your passive perception score when making stealth checks, this means those stealth checks are much less likely to succeed.
Taking the Alert feat prevents you from being surprised while conscious. This means you can still react quickly, even if enemies succeed on their stealth checks against you.
The feat’s +5 bonus is also extremely helpful here. Not only will you be able to act on the first round of combat but you’ll probably be early in the initiative order.
It’s worth noting that characters with the Alert feat can still be surprised while unconscious. Characters with high passive perception can be disturbed by sounds in their sleep (see Xanathar’s Guide to Everything, p77).
In this situation, high passive perception will be more effective at preventing Surprise.
Players can also avoid being Surprised by taking various preparations to guard themselves.
Traveling in daylight and sticking to open terrain rather than woods or forests will allow players a clear lookout in every direction.
Enemies can only attempt stealth checks if they could plausibly remain unseen so this makes it much more unlikely that they’ll successfully make their sneak attack against the party.
Players can also take turns to keep a lookout at night, clear foliage around their campsite, or set up lighting overnight.
As a DM, you should reward players who take any of these steps to safeguard themselves. If your party play in this kind of hyper-vigilant way, you should vindicate that by setting up some attempted ambushes for them to foil.