As explained in The Character Turn, you typically have an action, a bonus action, and your movement. You can use one of the following actions, an action gained from your class, magic item, or trait, or an action that you improvise. Many monsters have action options of their own in their stat blocks.
When you want to perform an action not detailed here, the DM determines whether the action is possible and what kind of roll you need to make to
determine if you succeed or fail.
Below is a list of the commonly utilized actions in a combat situation. Other rules, such as spells, features, or magic items might offer other actions, but are covered in detail in their individual rules.
Improvising an Action
Your character can do things not covered by the actions in this section, such as breaking down doors, intimidating enemies, sensing weaknesses in magical defenses, or calling for a parley with a foe. The only limits to the actions you can attempt are your imagination and your character’s ability scores. See the descriptions of the ability scores in the Using Ability Scores section for inspiration as you improvise.
When you describe an action not detailed elsewhere in the rules, the DM tells you whether that action is possible and what kind of roll you need to make, if any, to determine success or failure.