How does combat start when one PC is not seen as a threat?

Question

Imagine a party of four - three honest characters standing face to face against three evil bandits, one sly, backstabbing type some 30 ft behind the bandits' backs; the bandits may know he's there, but they don't know he's a part of the threat (or part of the party) and have little reason to pay attention to what he does.

He, while situation between bandits and heroes escalates, takes out his crossbow and declares attack. Roll initiative.

The question is what happens next?

How I (clumsily) solved the situation: I let the back-shooting character go first and then followed order of the initiative, where I skipped that characters first regular turn (so that he doesn't go twice).

What seems to be a common argument is that the initiative reflects how fast everyone reacts in situation where everyone tries to go at once (everyone wants to go first). But I am not sure this directly applies, since the initiating character is "outside the stand-off".

Related questions:

How to resolve surprise and "instant actioning" initiating combat

When and how does combat start in a standoff?

What the questions do not resolve is the effect of the character that is not seen as a threat and that is the main part of my interest.

Answer 1

In this scenario, your bandits were no doubt taken by surprise when one of them got shot. Unless there's some sort of telepathy or pre-planning involved, I would've ruled that the other PCs were also surprised.

In this case, for the first round all combatants bar your shifty PC are surprised (which is sometimes helpful to think of as a condition), meaning they miss their turn. During that turn, Mr Shifty shoots one of the bandits with his crossbow. At the end of the round, No one is Surprised and we follow on with normal combat. Thus according to my ruling, your PC would get one extra action. That's not that big a deal really, and your decision to just have Mr Shifty act first, out of turn, was reasonable.

Answer 2

RAW, this would have been handled differently

What your situation boils down to is whether the Bandits are surprised by the back-shooter or not.

Let's take a look at Surprise on initiative (taken from 5eSRD.com):

Surprise

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 GM determines who might be surprised. If neither side tries to be stealthy, they automatically notice each other. Otherwise, the 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.

Emphasis mine.

Now, if all three bandits know the back-shooter is present (and assuming that, like most bandits, everything they don't know is a threat to them) they are not surprised by the attack and combat ensues without any initial strikes occurring.

Why did I say strikes?

Your backshooter's friends most likely know know he plans to flank the bandits. They may not know when exactly the attack may fire, but they're prepared for it and wouldn't be surprised when it finally strikes.

As stated above for Surprise initiative is rolled for everyone participating in this encounter. Each of the bandits that did not know the backshooter was present (stealth vs perception) will be surprised. The first round will begin, as it was rolled. If a bandit that is surprised gets his turn he "can't move or take an action on [his] first turn of the combat". This also means that any member of your party (which shouldn't be surprised) can take their turns and actions normally, even if their initiative puts them before the attack of the backshooter.

The important factor of this situation is who is suprised and not what suprised them. It does not matter if it is a crossbow bolt arcing through the air, the roar of a dragon or a nearby explosion (an exploding keg of whiskey, an illusion or some magic combustion); if you can reasonably rule that something can surprise someone and they are not prepared/preemptively aware of it, they are surprised and can not act or move on their first action.

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P.S. People often say there are no surprise rounds in DnD 5e; and that's correct, when it comes to the specific term. You don't automatically snag yourself a full set of actions for each ally if you surprise only one enemy creature. That statement, however, significantly complicates how many people interpret surprise.

Answer 3

If the bandits know he's there, and the player declares he's attacking, then simply roll initiative between the rogue and the bandits. You have a PC skulking about who suddenly draws his crossbow. The resultant initiative order reflects the various levels of suspicion and reaction time on both sides of the fight.

At this point the rest of the characters are not participants in the fight. If they declare that they're joining in, or if the bandits attack them on the assumption they're all part of the same threat, then they roll initiative as well.

If the bandits don't know the rogue is there when he attacks, still roll initiative, but the bandits are surprised by the skulking rogue and do not get to act in the first round of combat. The rogue also receives whatever advantage is appropriate for attacking from hiding. The other PC's are still not participants until some action on their part or the bandits' part makes them so, at which point they roll initiative and join the fight.

Answer 4

Roll for surprise using Deception and Insight

If the rogue was trying to stay out of sight entirely then you'd determine his success with a Stealth vs. Perception check at the time he declares his attack. (Your choice whether that's rolled Stealth against passive Perception or the other way around.) Then roll initiative as normal, but everyone who failed the Perception check is surprised. This might result in someone not being surprised, beating the rogue on initiative, and getting to go first.

In this case he's trying to blend in. Instead of Stealth vs. Perception, do exactly the same with Deception vs. Insight. Anyone who passes this check noticed that he's suspicious and had their eyes on him. (This is a Deception check because the rogue is in plain view, but trying to hide his intent.)

In either case, if the rogue informed the other PCs of his plan, I'd give them advantage on their check.

Answer 5

As an alternative way of thinking about it:

Combat and Initiative is for when timing matters

Any time timing is important, whether or not it involves actual fighting, roll initiative for every one involved in the scene and go into the combat rules.

In the case above, I would have had everyone roll initiative as soon as the archer's player announced an intention to shoot.

If the bandits get to go before the bowman then I'd just say that something warned them. Maybe they heard the bow creak. Maybe they saw one of the three characters glace over their shoulder. Maybe they just got lucky. In any case, they get to resolve their action before the bowman does.

No Surprise

I would not roll for surprise for the bandits because they have already noticed a threat - the 3 adventurers standing before them.

Surprise is when you don't notice any threats, not for when you miss some of the threats.

As an aside, I would never let an unnoticed archer have a "free turn" before rolling initiative. Some classes get important features on the first turn of combat (e.g. assassin rogue, gloom stalker ranger) so if you deny them that first turn then you screw over those classes.