Make a self-control roll whenever it would be wise to deviate from your goal. If you fail, you continue to pursue your Obsession, regardless of the consequences.
You must make a self-control roll any time the GM feels you show an unreasonable degree of caution. If you fail, you must go ahead as though you were able to handle the situation!
Make a self-control roll whenever you have an opportunity to indulge your desires and know you shouldn’t (e.g., because the prisoner is one who should be released unharmed). If you fail, you cannot restrain yourself.