A combat encounter begins when the GM tells the party to “Roll Initiative!” Each hero rolls 1d20 and adds their Initiative bonus (typically their DEX). A single digit means they start combat with 1 action. 2 digits, they start combat with 2. A result of 20+ (or a natural 20) means they get all 3 actions!
Regardless of what a hero rolls on Initiative, at the end of their turn they gain all 3 actions back.
Surprise
Occasionally a party may maneuver themselves so adeptly that their enemy is completely caught off guard. In this case, the GM may grant the party advantage on Initiative, or in extreme cases, they may not need to roll Initiative at all—the GM can allow each Hero to start with all 3 actions!
If the heroes are surprised, they may have to roll with disadvantage. Or, in extreme cases, the heroes may automatically start combat with only 1 action, or the monsters may all go first.
A Note on Surprise
Merely being hidden or punching first is not sufficient to gain Surprise! If an enemy is on guard or at all aware of your presence, they cannot be surprised.
Turn Order
When combat begins, by default, the heroes go first. Whichever player is ready first goes first (or whoever makes the most sense story-wise), with play proceeding around the table clockwise. Monsters will typically act last, though some monsters may be fast enough to act sooner in the round. A monster (or monster group) should act at the same time each round.
Encourage teamwork, be flexible
If players want to strategically switch their turns for one round to facilitate teamwork or execute a tactical plan, the GM can allow this at his/her discretion. This should be done only occasionally, though, to avoid slowing the game down or losing track of who has taken their turn.
Playing virtually?
You can go in webcam order, alphabetically, or however is easiest to track!
Turns, Rounds & Encounters
A Turn is when 1 individual hero or monster group acts. A typical turn takes roughly 6 seconds of “in-world“ time. A Round is when all players and monsters have taken a turn acting. An Encounter is all of the rounds in a particular combat.
1/Turn Abilities. If you perform one on your turn, and can find a way to perform it on another creature’s turn, you can do it again (e.g., Sneak Attack combined with Opportunity Attack or Coordinated Strike!).
1/Round Abilities. These reset whenever your own turn begins (e.g., when you Defend, you cannot do so again until your turn comes back around).
Acting Over Multiple Turns
For activities that cost more than 1 action, your actions can be spent over multiple turns in combat as long as Concentration is maintained and you do not perform other actions or reactions in the meantime (unless they are free).
Example
Book, the Mage, wants to cast Glacier Strike (3 actions), but only has 1 action left. He’ll spend 1 action on this turn to start casting the spell, and on his next turn spend 2 more to finish casting it. He’s taking a risk, though: he can’t Defend himself and may need to rely on his party to protect him.