Initiative determines the turn order of combat or other turn based situations. To roll initiative, roll a d20 and add your dexterity attribute modifier; also known as your Initiative Modifier. There is a special space on your Character Sheet for your Initiative Modifier, as some things may affect it, such as the Thief class’s Nimbleness.
The higher the total, the sooner your turn arrives. For example, a 16 Initiative acts before a 15, a 15 before a 14, and so on. Once the last creature in the order has finished their turn, the creature at the top of the Initiative Order begins their turn.
Allies with the same Initiative may act at the same time. If the allies choose not to act at the same time, the ally with the highest Dexterity Modifier goes first. If this still results in a tie, a tiebreaker contested Dexterity Check is made to determine the Initiative.
If a player character and a non player character share the same initiative, the player character acts first.
A character can only have their turn once per round, even if their Initiative is moved in such a way that the turn order would pass over them more than once. Usually this occurs via class features, such as those found on the Jester or Captain subclasses.
If the DM wishes, they can opt to use Alternative Initiative, in which every creature acts simultaneously every round.
Initiative order is used to determine the order in which creatures declare their actions in this form of Initiative. Every creature in Initiative states what actions their turn will consist of, and once all actions have been declared, the DM resolves and realizes the declared actions the best they can. Effectively, the DM and the players hold on to their dice until all actions have been declared, then the creatures make their actions, then they resolve the actions, when can be reacted to using reactions. Once all actions and reactions have been resolved, the round ends, and the next one begins.
This method makes combat more immersive, and changes the tactical aspects of combat, as it makes it more difficult for players and enemies to actively react to what's happening on each turn, more realistically portraying the 6 seconds that make up a round.
In this optional rule, the DM shuffles the Initiative Order at the beginning of every round after the first one. This can be done in a number of ways, one of which may suit your game’s needs:
Rerolling Initiative for each creature at the beginning of each round - Lengthy, takes Initiative bonuses into account. Most accurate.
Assigning a playing card to each creature in Initiative, adding them to a deck, shuffling, and drawing from the top to see which creature’s turn is next.
Using software to shuffle initiative randomly.
Initiative shuffling adds a level of randomness to the order in which a combat occurs, which can prevent a player from being hard stuck in an unfavorable initiative.