Action Point(s), or AP, are a limited resource used to accomplish an Attack or Ability during a creature's Turn. These Action Point(s) are spent and and are potentially reduced to zero, automatically ending the creature's Turn.
Action Point(s) and the Reaction are reset at the start of the creature's Turn.
The default amount of Action Point(s) a creature gets is 3.
Legendary creatures gain Legendary Action Point(s).
Action points are used when in combat.