Are creatures in combat aware of the effects of others turns' in the same round before they begin their own turn?

Question

I have never played tabletop D&D before. Lots of NWN and BG on my PC though, so I know the basics. I got a 5e D&D "Essentials Kit" for my birthday and I'm going to try to run a beginner module for my family.

I am confused on the mechanics of combat. Everyone rolls for initiative and takes a 6 second turn in that order. I don't think that means every creature in the encounter takes a consecutive 6 second turn (does it?).

I am envisaging this:

Fighter - I run the length of the room and attack the nearest kobold with my sword (dice rolls, resolved)

Paladin - I do the same thing (dice rolls, resolved)

NPC Kobold - (roll to see who it attacks) attacks Paladin (dice rolls, scores some damage on the Paladin)

Cleric - I cast Healing Word on Paladin, then I go hide round the corner

So then which of these apply:

1. DM - "OK roll for your heal spell"

or:

2. DM - "Wait a minute, when you started your heal, neither of the PCs were even in combat yet, how did you know which one to start healing? I am going to rule you chose one at random and will toss a D2 to decide if you guessed right."

or even worse:

3. "You heal the Paladin and your spell lands just as he closes with the kobold, but since he was at full HP at the time...nothing happens."

It's a question of "do the creatures in combat see the effect of prior creature's six seconds of activity before they commence their own?"

Answer 1

The Combat section of the SRD (System Reference Document - to summarize greatly, the SRD is the "open source"-ish rules of the game without content that is specifically copyrighted outside of the SRD: fluff text, proper names, a handful of specific monsters, etc.) goes into greater detail, but the salient piece is this:

The game organizes the chaos of combat into a cycle of rounds and turns. A round represents about 6 seconds in the game world. During a round, each participant in a battle takes a turn. The order of turns is determined at the beginning of a combat encounter, when everyone rolls initiative. Once everyone has taken a turn, the fight continues to the next round if neither side has defeated the other.

(emphasis mine)

That is, when the cleric casts Healing Word, the kobold's blow has already landed and the paladin has been injured. Healing Word then heals some of the damage the kobold inflicted.

D&D (with, probably, a couple of exceptions) doesn't force anyone to maintain any "game state" other than the way things are "right now" - at the beginning of the cleric's turn, the paladin and fighter have closed with the kobold and the kobold has dealt damage to the paladin "right now". But, the game doesn't look backwards to see what the state was like prior to the current creature's turn when the "active" creature is determining what it can do.

This is why Readying exists: they allow characters to respond to things that happen while it's not their turn, tweaking the order of events in combat at the cost of doing something "now" and the possibility of losing the action altogether. Were it the case that the cleric went first, they could have readied Healing Word to affect whichever ally was first injured, but they couldn't also have hidden behind the corner (since they wouldn't be able to target either of their allies) and their allies might not have been injured, so the spell might have been lost with no effect. Note that there are definitely times when readying an action is a good call; this specific instance just wasn't one of those times.

Answer 2

The rules take a chaotic, simultaneous situation and break it up with the initiative roll, with each PC/NPC acting on their 'turn'. This is what gives the battle a logical consistency; otherwise, it would be madness.

So, although each PC/NPC isn't really waiting in a nice orderly line to state their actions, that is the way it is handled. Without that the battle would be awful to try and control.

So, yes, by the time the Cleric takes their turn, the Paladin has taken damage and they can cast their spell.

This is where reactions are important as they allow a PC/NPC that has already had their turn in that round respond to events that happen afterwards.

Answer 3

So then which of these apply:

It's this one, definitely this one:

DM - "OK roll for your heal spell"

Also, the answer to this question is emphatically yes:

It's a question of "do the creatures in combat see the effect of prior creature's six seconds of activity before they commence their own?"

Everyone takes their six second turn based on the scene as it has been modified by previous actions on previous turns. Each turn includes the decision to act, the action, and the resolution of the action by the DM.

You do have to worry about "reactions" which are instant responses that can happen on someone else's turn. But the general conceptual model is sequential turns with sequential action declaration.

(There are systems, usually wargames or computer games, that work the other way with everyone declaring actions up front at the same time. D&D is not one of them.)

Answer 4

Other answers cover the question itself in more detail, but for completeness: yes, each creature knows the results* of all previous turns before they make their choices.

But I think one thing that's confusing you is that six second turn detail.

The way I'd look at it is this: it's six seconds from the start of a creature's turn to the start of that creature's next turn. It's not quite "each creature's actions take six seconds" - which would result in each full round of combat with four PCs against six goblins taking a full minute. In-world, most of this is happening at the same time, but the mechanics break it into turns to make it easier to play out as a game.

In your example, the Fighter starts running across the room, and the Paladin follows to attack the kobold, who stabs one of them back; the Cleric is a little slower to get moving, but they cast that spell and then duck round the corner. At this point, about six seconds have passed from the start of the fight, and we're back round to the Fighter.

In a movie we'd definitely see the Paladin start running before the Fighter swings at the kobold - we just abstract that away to make the turn system work, because simultaneous actions are much more complicated to design a system for.

*(Other than anything explicitly secret like the location of hidden enemies whose Stealth roll you didn't beat, but that's outside the scope of this question.)