Turn-based mode is one of the two gameplay modes in Baldur's Gate 3, in which time passes in turns and rounds, as opposed to real-time mode, where time passes in real-time.
Each round, the game cycles through each participating creature's turn, during which each creature may move or actions. One round has passed when all creatures have taken their turn.
Turn order
Each creature makes a 
d4 + Dexterity modifier roll when they enter turn-based mode. This is called rolling for initiative.
Each round, the game cycles through the turns of all participating creatures in descending order of their initiative.
Simultaneous turns
Allied creatures usually take their turns at the same time when they are in close proximity to each other and are directly adjacent to each other in the turn order. Up to a maximum of 10 creatures may take their turns interchangeably in this way.[note 1]
Surprise rounds
If an attacked creature is unaware of their attacker at the start of combat – such as if the attacker is hidden – the first round of combat is declared a surprise round, and the attacked creature is surprised.[note 5]
Surprised creatures have the 
condition for the entirety of the first round, and cannot take actions or reactions until the start of the second round.[note 6]
Creatures with the Alert feat or 
feature cannot be surprised.[note 7]
Action economy
When taking their turns, creatures are able to move a distance up to their movement speed, and can expend their available resources to take actions.
Actions are generally taken in order to deal damage or inflict harmful conditions, but they can also be taken to heal or aid allies.
Most actions require the creation to expend one of three resources:
Action
Bonus action
Reaction
By default,[note 8] a creature has 1 charge each of these three resources that always recharges at the start of the creature's turns.
Reactions
Reactions are a form of action that can be taken by creatures as a response to certain triggers, including on the turns of other creatures. These often require the acting creature to spend a Reaction charge.
Footnotes
- ↑ Summoned creatures that are not controlled by their summoner are nor considered allies, and thus do not get to take their turns at the same time as their summoner.
- ↑ The first encounter with the imps during the Prologue always grants the player a surprise round.
- ↑ Mimics always surprise the party when interacted with in their disguised form.
- ↑ In the Underdark Beach, a duergar might spot the party and summon their own leader. The party is surprised if they choose to wait for the leader, whereas if they attack, the duergars are surprised instead.
- ↑ Certain combat encounters are rigged to always Surprise either the player's party or the enemy party when the proper conditions are met.[note 2][note 3][note 4]
- ↑ While surprised creatures are unable to take actions, some can warn nearby allies, preventing them from becoming surprised too.
- ↑ The
Elixir of Vigilance also gives temporary immunity to being surprised.
- ↑ Additional resources can also be acquired through various means.