Grand Duke / Tai Sui (太歲) or some text call it 歲星 (sometimes called Grand Duke Jupiter). This is the main controller for the year or the governing energy force for the year.
Opposite the Tai Sui or Grand Duke of the year is what is known as the Year Breaker 歲破 (Sui Po). For example: Ox Year (丑年), so opposite Goat (未日), this is deem as the Year Breaker Dates. In this example, the energies are not supportive / complimentary but are oppositional. As such, there is a lot of tension in breaker dates; the situation appears difficult and feels uneasy or antagonistic nature.
If this dates have to be use, the user should expect headwinds, challenges, and minor problems surrounding the event or rework regarding a project. Year Breaker Dates are rarely use for commencement of renovation, weddings and Feng Shui Assessment/ Audit.
In market practice, it is not uncommon that Feng Shui Masters and Practitioners adopt the use of Month Breaker Dates (月破) as well. Because of the proximity between the Month to the Day vs Year to the Day, the energy vibration in Month Breaker is much stronger/ higher but shorter in tenure/ duration. Therefore, the negative impact (when use) is strong and sudden but seldom long-lasting.
This give an image of Duke / Governor ( 太歲 ) who rules the city and set the policies while the General / Officials (月将) are the administrators who run the rules and polices the crooks.