翻手為雲覆手雨

fānshǒuwéiyúnfùshǒuyǔ ㄈㄢ ㄕㄡˇ ㄨㄟˊ ㄩㄣˊ ㄈㄨˋ ㄕㄡˇ ㄩˇ

    • to be fickle and ever-changing
    • to wield great power and manipulate others at will

Character by character

Saying俗语俗語

Idiom惯用语 · Widely known

Literally
turn the hand over for clouds, turn it back for rain
Meaning
Describes someone fickle, whose words and acts change constantly, or who wields great power. Critical.

Sources