The EventGraph of a Blueprint contains a node graph that uses events and function calls to perform actions in response to gameplay events associated with the Blueprint. This is used to add functionality that is common to all instances of a Blueprint. This is where interactivity and dynamic responses are setup. For example, a light Blueprint could respond to a damage event by turning off its LightComponent and changing the material used by its mesh. This would automatically provide this behavior to all instances of the light Blueprint.