the Vishnu Shakti (preservation) of ALMIGHTY GOD(PARMESHWAR) better known as NARAYAN ,VISHNU,

The vishnu one of the three Gods from the holy Trinity,the major work area is preservation of whole universe
The number of auspicious qualities of Vishnu as the supreme God power of three great trinity  are countless, with the following six qualities being the most important:

• Jñāna (Omniscience), defined as the power to know about all beings simultaneously
• Aishvarya (Sovereignty, derived from the word Ishvara), which consists in unchallenged rule over all
• Shakti (Energy), or power, which is the capacity to make the impossible possible
• Bala (Strength), which is the capacity to support everything by will and without any fatigue
• Vīrya (Vigor), which indicates the power to retain immateriality as the supreme being in spite of being the material cause of mutable creations
• Tejas (Splendor), which expresses His self-sufficiency and the capacity to overpower everything by His spiritual effulgence

the lord vishnu takes avatara ;incarnations when there is fluctuation of justice on earth ,and destroys all immoral people .He is considered as supreme between three great trinity because "HINDUS BELIEVE IN PRESERVATION RATHER THAN DESTRUCTION BUT IT DOESN'T MEAN THAT WE ALLOW INJUSTICE ".