You can perform calculations and validations in every activity of the process with the Activity Actions option found in the fourth step of the Process Wizard (Business Rules).
These Actions can be executed when the Case enters the Activity, when the end user clicks on the Save button, or when Case leaves the Activity.
Thus, actions can be created in the following moments:
•On Enter: Once, as soon as the Activity is created
•On Save: Every time the end users clicks on Save or when the Task is refreshed. (Applies to tasks where an end user interacts with the Process: Tasks and Intermediate Events)
•On Exit: Once, when the Activity is finished.
Actions related to Business Rules are also known as Expressions.
What you need to do in Bizagi
As soon as the Actions option is selected the Process flow will be displayed.
The tasks that have actions related will have a special mark, according to the type of action that has been associated.
You can click any task to include an Action.
Since conditional tasks do not need an incoming connector (process flow), No conditional task can have an On Enter behavior regarding Activity Actions.