Translated from here.
In addition to Ming and the other 11 palaces, there is Shen Gong. Shen is an auxiliary palace. The Shen palace will always overlap with either Ming, Happiness and Virtue, Career, Travel, Wealth, or Spouse.
The impact of Shen in the horoscope can be divided into three main influences:
1) Revision [修正 = to revise, correct, amend]
To find out about one's fate, the Ming palace is primarily scrutinised. It will be operative from start to finish. It is one's pre-natal fate. But Shen will gradually become more and more important, and at the age of 35 onwards it will be in full effect.
For example - If a person's Ming palace is weak, but Shen is strong, the individual will experience toil and unfavourable circumstances during his or her younger years [the first half of life], but with the arrival of the impact of a vigorous Shen palace [the second half], gradually the native will enter the most pleasant and enjoyable stage of his or her life.
Conversely, should Ming be strong and Shen weak, first the person will meet with magnificence and abundance, afterwards experiencing a decline and the coming of feebleness.
2) Increase [加強 = to strengthen, augment, enhance, reinforce, intensify]
The position of Shen in the horoscope will mean an increase in good and bad luck in the matters of that area of life.
For example - Should the Shen palace share palace with the Spouse palace, the auspicious and unfavourable regarding that area of life, i.e. love, romance, and relationships, etc., will become more pronounced compared to the other palaces in the chart.
3) Contrast [對比 = to contrast, balance; a contrast, comparison; a ratio]
Ming and Shen will be important throughout one's life. But it is also possible to use these two palaces concerning stuff to do with everyday living. During the course of an undertaking, endeavour, venture, activity, there are frequently changes in the way one goes about conducting the matter. The Ming palace is then a representative of the first half of the process, Shen the latter half.
For example - An individual has Wu Qu and Tan Lang in Ming, also seeing Di Kong. Zi Wei and Qi Sha are in Shen. During the first half of the undertaking, the native is... [?], and hesitant and indecisive. But during the second half, the person becomes persistent and will be of the ability to implement stuff and carrying out things.
However, should the case be the other way around, there will be the instance of 虎頭蛇尾 hǔtóushéwěi = a strong start, but a weak finish; a tiger's head, but a snake's tail; to start off with a bang, but end up with a whimper; to begin with a flourish, but peter out towards the end.