Foreword: this form is a UX nightmare in itself. My task is not to make it better, just to show a required field.
I have a form in which the user can add multiple lines to a dynamically added group of data called "activities". These lines ultimately become the budget for said activity.
Each of these lines come with a field called "justification". This field is required to be entered by the user, or else he won't be able to save his work.
The highlighted column is the required field. As previously stated, this is the only field in the whole form that will prevent the user from saving.
So, how do I indicate to my user that this field is required in a sea of other fields that are not?