If an attack alerts someone to your presence, can their initiative save them from being surprised in time?

Question

In D&D 5e "Surprise" is a condition that can affect a creature during the first round of combat, only until the end of their turn:

[... T]he GM 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 reaction until that turn ends. A member of a group can be surprised even if the other members aren’t. - PHB 189

Does the action that causes the surprise count as part of the round, though?

Say Renee, a rogue, achieves a stealth check of 22, easily beating an orc sentry's passive perception. She sneaks directly behind him and stabs him in the back. Surely the orc isn't surprised at all until the dagger hits him (or if Renee misses, she fumbles around behind him or something).

What I think it really boils down to in the end is: when is initiative rolled? If (in our example) initiative is rolled before Renee's attack hits (or misses) how can we justify the orc recovering from his surprise before the action that triggered said surprise even occurs, should he roll better than Renee on his initiative?

I'd like to go with initiative is rolled immediately following whatever event began the encounter (which could be an attack, but is likely to often be something else wherever surprise isn't intended), but I can't find any documentation to support this stance.

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Why Does Anyone Care?

There are many reasons you might want someone to be surprised while you're attacking - in this example if Renee is over L3 (and took the Assassin archetype) she'll get 'Assassinate' if the orc is surprised, and 'Death Strike' if she's over L17. That's a lot of potential extra damage!

J.E also pointed out that if the orc is surprised, Renee will be able to retreat and hide, without having to take the disengage action as her bonus action to avoid an attack of opportunity. Of course, there's no way for her to know whether the orc is surprised or not at that stage, so trying this would be a bit of a gamble...

Answer 1

The initiative rolls can be interpreted as a metaphor for other circumstances. So if the orc rolls high, imagine that as him turning his head ina lucky timeframe, just to see the attacker in the corner of his eye. But he is still surprised, so he does not get to act first.

To answer: the action that causes the surprise does count as a part of the round. The initiative is rolled when it is obvious that a combat should start, i.e. when one of the players or the DM decides to attack. Whether you roll it before or after determining surprise is of no consequence. But it is definitely rolled before the first attack (the back-stab in your case).

See e.g. this question. By the rules, it would go like this:

• Two opposing parties meet (Renee meets with the orc sentry) with intention of combat (Renee want to stabby-stabby).
• The DM decides which parties are surprised (the orc is, probably).
• Initiative is rolled. Now there are two possibilities – either Renee beats the orcs initiative or vice versa.

If Renee "goes" first: Renee uses her round to abuse the poor orc. Then the orc's round comes up, he cannot use any action or move on this turn and he couldn't have used any reactions up to the end of it (so for example if Renee moved away after the stab, she would get no attack of oportunity). From now on, combat goes as usual, next turn is Renee's.

If the orc "goes" first: The orc cannot do much on his round, since he is surprised. So his turn ends. From now on he can take reactions and normal actions on his following turns. Renee goes next and she spends her turn with the backstab (if she wants to). If Renee then wanted to move away from the orc, the orc could use the attack of opportunity on him. From now on, the combat goes as usual.

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How this affects assassinate: If Renee beats the orc's initiative roll, she gets both the advantage (since she takes his first turn before the orc) and the crit (since the orc is still surprised)

If the orc goes first, Renee gets neither, since the orc is no longer surprised by the time Renee gets to her turn.

Answer 2

As the quoted text says, the orc starts the encounter with the surprised condition. The encounter is run as usual: Both roll initiative, and the orc does nothing during the first turn. Even if his initiative is higher. In his turn, the rogue stabs the orc. At the end of the first round, what happened is: The rogue hit the orc which could not do anything due to the surprise, which makes sense

Answer 3

It's not definitive when Surprise actually ends

It's true that surprise doesn't state it goes beyond the first turn of combat.

While it doesn't state that Surprise can continue, it just talks about being Surprised and then provides some mechanics.

This leaves you with a standard initiative round in which one are more creatures are surprised/able to act until the next round begins.

My read on this as that while some mechanics do end after the creature's turn - being surprised doesn't.

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.

There is no specific language here about being surprised ending, but there are some possibilities:

1. Surprise ends because the creature is able to take reactions at the end of their turn.
2. Surprise continues until the beginning of the fresh initiative round

Given the wording, it is unclear which is correct and both cases are legitimate.

Rules as Fun

For the most part, this will most matter on creatures that gain additional benefits when acting on a surprised creature. Most of those times it is more likely that PCs are doing so - and you should let them. Surprise is already a seldom-available mechanic, so let's not further nerf it by making it 100% contingent on an initiative roll.

The Assassin Rogue's Assassinate feature is a good example:

Starting at 3rd level, you are at your deadliest when you get the drop on your enemies. You have advantage on attack rolls against any creature that hasn’t taken a turn in the combat yet. In addition, any hit you score against a creature that is surprised is a critical hit.

In this case, the even if the surprised creature rolls a higher initiative, they'll still be able to use their class feature. They'll lose the advantage because the creature has still taken a turn, but they'll still be able to auto-crit on a successful hit.