More info about the parameters of this action here.
Run the selected Tasker task.
You can 'nest' as many tasks as you wish.
When this action is used as part of an Enter task, the settings it contains are *not* restored when the profile exits.
When a task is started from an existing task, the existing task continues unless the Stop parameter is set.
If you set the priority lower than the current task, the current task will finish before the new one starts.
If you set the priority the same or higher than the current task (a good way to do this is to specify '%priority+1'), the new task will completely execute before the current one resumes.
Values assigned to %par1 and %par2 are available in the child task as normal variables.
If the child does a Return action, the Return Value Variable in the parent task is set to the Value specified in that Return action, however note that the value will not be returned if the Perform Task is the last action of the parent.
See Flow Control in the Userguide for more info.
When you add an action in a task you can use the search field in the dialog to search for a task name directly and then select the
Perform Task action to have the task name filled in automatically.
If you do this when adding a favorite action (long click the + button in task) you can have a direct shortcut to the specific task you searched for.
Check out a demo for this here