The caster continues casting the spell.
Taking the same quotes from @Xirema's answer, we have the following for casting spells with a long casting time:
Certain spells (including spells cast as rituals) require more time to
cast: minutes or even hours. When you cast a spell with a casting time
longer than a single action or reaction, you must spend ...
You take your turn and can act as normal
The Weapon of Warning (DMG, p. 213) states:
[...] you and any of your companions within 30 feet of you can't be surprised, except when incapacitated by something other than nonmagical sleep. [...]
You have stated that your companions were all outside of the range for this effect, however that does not prevent it ...
The narration of the event seems strange to you because you are confusing the planned order of events with the actual order of events.
The plan was that the encounter begins when A throws their dagger. So if the characters had followed the plan then the order of events for round 1 would have been:
X does nothing because they don't know they are in an ...
The Spellcaster would lose the spell
This is relatively straightforward. The rules for spellcasting state unambiguously that a caster casting a spell with a long casting time must use their action each turn to cast it:
Certain spells (including spells cast as rituals) require more time to cast: minutes or even hours. When you cast a spell with a casting ...
Yes, That Description is RAW
That is the way mechanics happens in RAW. How you narrate that to make sense is up to you. Remember the rules have to be turn based to make it run and everything that happens in a round is happening inside 6 seconds and at roughly at the "same time".
Two Common Alternatives
There are two common alternatives I've seen:
No, a surprised character can't drop prone
As you posted, Surprise says:
If you're surprised, you can't move or take an action...
This "can't move" terminology is actually used a lot in the rules. A few other examples:
The creature is incapacitated (see the condition), can't move or speak, and is unaware of its surroundings.
A surprised monster who rolls a 20+ on initiative can use lair actions because they are able to take actions, and their turn has passed
As you've quoted, the rules on lair actions state:
On initiative count 20 (losing all initiative ties), it can use one of its lair action options. It can’t do so while incapacitated or otherwise unable to take actions. ...
They follow the command if they are able to
The surprised condition prevents a creature from taking an action, moving or using a reaction until the end of their turn. Any command that requires a creature to do one of these thing will count as the target not be able to follow the command. Therefore the spell will fail. Not all command options require an ...
RAW: Yes, and that's fine
The relevant excerpt from the Player's Handbook (p. 189):
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.
Which would mean a creature which for whatever reason was moving before Initiative was rolled, does not move during its first ...
Surprise is very much up to the GM
How does surprise work?
The section on "The Order of Combat" states:
1. Determine surprise. The DM determines whether anyone involved in the combat encounter is surprised [...]
The section on "Surprise" states:
The DM determines who might be surprised. If neither side tries to be stealthy, ...
Your group is surprised, you aren't
Combat works like this:
Determine surprise. The DM determines whether anyone involved in the combat encounter is surprised.
Establish positions. The DM decides where all the characters and monsters are located. Given the adventurers' marching order or their stated positions in the room or ...
Your interpretation of the rule is correct
According to Chapter 9: Combat of the PHB/Basic Rules on D&D Beyond, under Surprise:
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.
After that turn (the surprised creature's turn) ends, it is then free to take a ...
Surprise is a specific term; it happens at the start of combat
The "Surprise" section of the PHB covers this mechanic:
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 ...
No, action surge can't be used while surprised in this context
Arcane Charge says:
At 15th level, you gain the ability to teleport up to 30 feet to an unoccupied space you can see when you use your Action Surge
To use an ability, you must do (and thus be able to do) whatever that ability is allowing you to do.
Action Surge says:
Starting at 2nd ...
Generally speaking, while in initiative order, creatures do not move when it is not their turn
Before I continue, I just want to make sure it doesn't go unstated that there are obvious exceptions:
Using the Ready Action and choosing to move when using their Reaction, instead of taking an Action
Being moved by an external force, like a spell or someone ...
Yes (at the end of the surprised enemy's turn)
Note that there isn't really a "surprise round" in D&D 5th edition. Rather, it is just the first round of combat but surprised creatures can't take actions or reactions until after their first turn (see here):
If you're surprised, you can't move or take an action on your first
turn of the combat, and ...
Flanking makes no difference here, it is restricted to the 1st turn
Surprise only counts at the start of the combat in D&D 5e. As we can read in the PHB about The Order of Combat on page 189:
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
The first part ...
The rule you quoted states :
Any character or monster that doesn’t notice a threat is surprised at the start of the encounter.
And according to you the situation is :
The creature [...] goes straight to its source, entering the room and exposing its back to the Rogue who, unnoticed by the creature, prepares to attack it.
Therefore the creature ...
Surprise rounds come from things like ambushes. If you're giving Janet and John surprise, then Dick and Jane should have had the chance to perceive that an attack was coming before the combat starts. Insight, Awareness, Streetwise…something that would allow them not to be caught by surprise.
If Dick and Jane each fail to detect the oncoming threat, then, ...
There is still certainly "surprise", though not quite a "surprise round".
See the surprise rules.
It is generally up to the DM whether there is a chance that one side (or some of the combatants) may be surprised.
The rules given are keyed towards one side being stealthy (rather than disguised) and so it becomes a Dex(Stealth) check vs a Wis(Perception) ...
When the opposing party is no longer expecting a threat.
Narratively, your BBEG is fighting the party, and runs away, yelling
You'll pay for this one day!
Let's say the party, being cautious, tells you, the DM,
Ok, the Druid is downing a potion on the poor Barbarian, while the rest of us scout the remainder of his room for Mimics. Paladin is in front,...
The issue I see in this scenario is that one player broadcasted their intent ahead of their turn, and the other did not, so the narrative only seems unusual because the decision of what's happening in the ambush was only partially made outside the context of turn order.
To resummarize my understanding of the narrative, A stated they wished to take a combat ...
None of the interpretations are correct, necessarily. While players can certainly take many kinds of actions outside of combat, like kicking down a door, activating a magic item or blindly shooting a flaming arrow down a dark passage, which very well may result in combat, the Ready action is generally not meant to be used outside of combat as a means of ...
The rules say:
If neither side tries to be stealthy, they automatically notice each other.
from which I conclude that any character that is not trying to be stealthy is automatically noticed. So all of the monsters have noticed your "not trying to be stealthy" character.
The rules say:
Any character or monster that doesn’t notice a threat is ...
Taking the rules very literally, the spell fails.
The caster doesn't get to take an action, so they don't keep casting the spell.
However, the rules are kind of dumb.
As usual, the 5e rules don't try to be comprehensive. They tell you what happens under "normal" conditions and leave it to the players to work out the edge cases.
Doing nothing while ...
No, surprise continues until the start of the next round - but some mechanics end at the turn.
The rules on surprise and the mechanics thereof are what they are.
Surprise doesn't state it goes beyond the first turn of combat. While it doesn't state that it can continue, the only wording involved is regarding the first turn. The logical next step is that ...
It is the same thing
The bugbear and the players each have a turn in the first round.
The Order of Combat (PHB p189):
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. ...
Once everyone has taken a turn, the fight ...
AD&D is mostly a system for determining what happens in situations we already understand, rather than dictating what situations are possible to experience in the game. There is no reason why a stealthy 3rd party could not approach a fight undetected, therefore it is possible.
You can determine whether there is surprise by making the usual roll: 2 in 6 ...
Yes, the Player’s Handbook and Dungeon Master’s Guide give some some examples of threats
Page 182 of the PHB has a section on noticing threats. An example of a threat it gives is “ a stealthy creature following the group“. The creature is not posing an immediate danger but they could potentially ambush the party if they were not noticed. This tells us that ...
If the Command requires an Action, then they are unable to follow the Command, and the spell ends.
Assuming that the Command would require an Action (or Movement) to complete:
Command is specific, in that it acknowledges that the target may not be able to follow the Command. It does not provide any method for allowing the target to act when it is otherwise ...