How to resolve surprise and "instant actioning" initiating combat

Question

DMed for the first time yesterday and one of the things I feel I need to sort out, among other comments, improvements, and similar, is how combat itself is actually initiated.

The main example I want to use involves instant actioning attempting to generate surprise conditions by players. Here the characters have entered a ruined city and generally been noisy about the whole thing - using a spell to make their voice louder and literally ask if there is anyone about. Any enemies around probably know what something is about to kick off but arguably don't know precisely what.

After resting the PCs head up a long flight of steps to a temple on the edge of the city. At the top only one crests and finds 3 bandits lounging around, chatting, and doing whatever bandits do in their spare time. After a brief exchange of pleasantries a combat starts:

DM "The bandit spits in your direction 'we're not done looting the temple, so you can clear off', and starts raising his crossbow as his mates emerge from their cover behind the pillars...

PC "I cast Firebolt at Bandit Keith"

DM "Hang on, I hadn't finished, everyone rolls for initiative...

Which sparked a debate about whether or not the PC could preemptively cast/attack before the combat starts by "instant actioning" (as above) as I was describing the start of the combat. As far as the bandits are concerned a lone half-elf who is pretty heavily armed has popped up in front of them, not even tried to be diplomatic, and ended up saying something rather suggestive about their mothers. The PC then asked about it being "surprise" because the bandits wouldn't necessarily expect an attack, but my view of "surprise" is closer to an ambush where one party is unaware of the other's existence.

(This precise example is close to how this question about standoffs works, however this specific PC was always the first of the party to go into rooms (only one with darkvision) and consistently felt they should get free rounds at the start of combat based on declaring attacks before I could "start" the combat.)

The second example the party came to more bandits, who were not alert immediately, in an underground room. They used magic to yell something obscene at the bandits and shut off all the torches so the bandits were effectively blinded. At this point they wanted to burst into the room casting spells, swinging maces, and playing some "meaty chords" (the bard's words, not mine). Again they wanted surprise arguing that, despite the fact that the bandits were yelling and cursing in confusion, they couldn't be sure they were actually being attacked as such. In the end a character with darkvision wanted to sneak in to a corner and again wanted surprise based on passing stealth rolls, so they would start the "combat" by firing a crossbow. At that point I think I relented because it was clear that they would do anything to try and win combats in a single round.

In a nutshell, my question is: "how liberally can the concept of surprise be applied to combat - is it only when one party is literally unaware of a threat (as I read the rules), or just when they are caught slightly off guard by the exact situation?"

NB I already plan to address the attempts at interrupting descriptions with actions next session, because it happened at other times and actually threw me off quite a bit.

Answer 1

You're in luck, because there are only 2 basic things said about when someone is surprised, and both are in your favor.

The first one is:

The GM determines who might be surprised.

So yeah, you explicitly get to decide in the end. If you don't think it's reasonable for the enemy to be surprised, they aren't.

The other one is:

If neither side tries to be stealthy, they automatically notice each other.

And your party does not seem to have any interest in being stealthy, so they don't get to surprise anyone.

There's one last part, that's also interesting and probably key to explaining why they don't get surprise, the next time it comes up. (Emphasis mine)

Any character or monster that doesn't notice a threat is surprised at the start of the encounter.

The question is not "Do they see an attack coming?" but "Did they notice a threat?". Meeting an unfamiliar person, in armor, while looting a dungeon is definitely noticing a threat, whether you see their attack or not.

Now if your player wants to stab the bandit in the face before he has time to act, that's what a high initiative roll is for, not a surprise round.

Answer 2

Surprise is not the same as initiative, and neither is taking the first action.

In the first example, I would say there is no surprise; everyone knows there are potentially hostile enemies present. So the first bandit gets to shoot first, once, and then everyone rolls initiative. His shot is not at surprise, so no one will miss any actions when their initiatives roll around, and no powers that depend on surprise (e.g. assassin rogue crits) would apply. Just one "free" shot to start it, and then off we go.

I would be fine with a player saying "I'm going to ready an attack, so that if the bandit so much as twitches, I'll take a swing/shot." In that case, when the bandit reaches for his crossbow, I would let the character take his readied shot, then the bandit (if he's still conscious) gets his shot, then we do initiative order. In the scenario given, the player hadn't readied a response, so the bandit goes first, when he decides to go.

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In the second case, I think there is surprise as the scenario is written, if the bandits are not aware of the party's approach. In this example, the initial action that starts everything is the shutting off of the torches. The room goes dark, and everyone rolls initiative, and the surprised bandits, each on their turn, will lose their first actions to being surprised. The sneaky guy in the corner does get the advantages of surprise on his first action, and he gets advantage for attacking from an unseen position (and if he has darkvision, and the bandits do not, and the room stays dark, he might well get several attacks with this advantage if he continues to successfully be stealthy).

The most I would give the party in this second case is that if a) the bandits remain unaware of them until the lights go out, and b) the party makes a careful plan and positions themselves for it well, and c) the characters all ready themselves and ready their actions with the torches going out as the trigger, then they could have had first action and initial surprise.

So in this case, I would run the scenario like this:

1. everyone in the party gets ready (initiative gets determined at this point),

2. the lights go out, and everyone in the party does their readied actions, with surprise,

   2a. all those actions must be those that can be readied, so they can't both move and attack, or use bonus actions, or do other things that can't be readied actions, then

3. proceed in initiative order, as normal with the bandits each missing their first actions due to surprise.

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So yes, if you completely get the drop on someone, they don't know you are there, you make a good plan, and no one messes it all up, it can be (and should be) devastating. But that is not (and should not be) easy to arrange. Those are some pretty unaware bandits, to let the whole party, in armor and everything, sneak up and fully position themselves without being noticed.

Also note, of course, that if the party is sufficiently un-vigilant, and a set of stealthy careful monsters get the drop on them similarly it can be equally harsh. The party in one of my 5e campaigns learned a good lesson on that, crashing through the forest with their horses and dogs and all that. They got ambushed by 10 ordinary orcs with crossbows, who heard them coming, hid, and were readied.

I told everyone to roll their initiatives. The orcs all had readied actions and popped up and fired. In initiative order, the party members all missed their first actions (except the warlock who has the Alert feat) and the orcs all took their second shots. Then initiative order again, with surprise no longer in effect, but some of the high initiative orcs even got a third shot off before some of the low initiative PCs got to take an effective action.

The party ultimately won the fight, but several PCs were unconscious by the end. 10 orcs with no special powers or equipment were able to give serious trouble to a party of 8 5th level characters at full strength.