Surprise and Sudden Actions
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 rollwith advantage.
If nobody is trying to be sneaky, combat begins normally with.