The initiative step sets the order of everyone's turn throughout the encounter. Each participant makes an ability check to determine their place in the initiative count, from the highest check total to the lowest. This ability check is typically Dexterity. The Narrator might determine that one or more participants should instead roll a different ability check, potentially utilizing a relevant skill or tool (see Table: Types of Initiative). In the event of a tie, the tied participants each roll a d20 to determine the order amongst themselves (the highest roll goes first.)

If any creatures have already made an ability check during the surprise step, they use that existing score for initiative.

The party lurks in the shadows of the cult’s ritual, looking for the right moment to cut it short. A sneaky athlete sprints ahead before the start of the race and the other racers catch on. A noble suddenly draws her sword and lunges at the king.

If some participants are unaware of others due to successful attempts to be stealthy, they begin the encounter surprised. The Narrator calls for appropriate ability checks to determine whether participants are aware of each other. Surprised creatures are unable to move or take an action on their first turn, and are unable to use a reaction until after their first turn.

Sometimes all participants are aware of each other at the beginning of an encounter, but one side takes an action or launches an attack while others' guards are down. In this case, no one is surprised, but the Narrator may allow the instigating creature or party to roll initiative with advantage.

If nobody is trying to be sneaky, combat begins normally with initiative .

All engagements using Turn-Based Action consist of two phases: set-up and initiative rounds. The set-up phase establishes the status and order of the participants and the amount of time each round takes in the game world, and initiative rounds are where the participants take their turns round after round until one side is victorious.

Set-up

1. Set the Scene. The Narrator decides where everyone is located, the appropriate amount of time for each round, and any important condition of the engagement. 
2. Surprise. If any characters intend to act before all participants are aware of the encounter, the Narrator calls for ability checks to determine if any combatants are surprised.
3. Roll Initiative. The remaining participants roll initiative and determine the turn order.

Initiative Rounds

1. World Actions. If the environment features any world bonuses or penalties with an active element, it occurs at the start of a round before the participants take their turns.
2. On Your Turn. The active character moves and uses their available actions.
3. Off Your Turn. The inactive characters plan their next turn and prepare to react to the active character's actions.
4. End of Round. When everyone has taken their turn, the initiative round repeats at step 1 until the encounter has concluded.

On Your Turn

When it is your turn, you can move a distance up to your Speed and take your actions. You can declare your intent for your turn in any order, breaking up your movement between actions or using your bonus action first. You can also choose to do absolutely nothing.

Within a single round, you can take an action, a bonus action, and any free actions (like communicating with allies, dismissing the effect of a thaumaturgy cantrip you have already cast, or interacting with an object) during your turn, and one reaction at any time. The rules for actions and movement are found in the Actions in Combat and Movement and Position sections of this chapter, respectively.

Off Your Turn

You're still an active participant in Turn-Based Action even when it's not your turn! You have a number of responsibilities to keep track of within an encounter in between taking actions.

1. Plan your actions so you're ready when your turn comes. Creatures who carry long lists of spells especially have a lot of options to manage, and you might not want to spend your precious 6 seconds flipping through a book.
2. Pay attention to the encounter beyond events that involve you. The priorities of you and your allies can change in the blink of an eye, and the actions you were planning can become inappropriate for the task.
3. Be prepared to use your reaction. Reactions have specific conditions that can occur at any time and you don't want to let a golden opportunity escape your grasp.

End of Round

Once all participants have taken their turn, the encounter returns to the start of a new round. The loop persists until the action concludes, or the granularity of Turn-Based Action is no longer needed.

Turn-Based Action provides a structure for all characters and creatures in the immediate area to engage with one another at the same time whether for combat or other dangerous scenarios. These rules refer to "you" and specify either the player or the character(s) you control. The Narrator controls all the nonplayer characters and creatures in Turn-Based Action while each other player controls their adventurer.

The most common use for Turn-Based Action is combat.

When to Use Turn-Based Action

Turn-Based Action can be called when a hostile action is taken, the characters enter a precarious location or situation, or at the start of a competition. Whenever methodical actions are necessary from multiple characters at the same time, this system presents the scene in a way that everyone gets the spotlight.

Setting the Scene

The Narrator establishes the conditions of any Turn-Based Action encounter. This includes the known participants and their positions, any active elements and known world bonuses or penalties in the environment, and the length of each round.

A round encompasses the semi-simultaneous actions of the participants within a period of game world time. For combat, one round is usually 6 seconds. In other cases a round might take 10 seconds, 1 minute, or 10 minutes as deemed appropriate by the Narrator.