They said you could not improve on Perfection - Cosmos said “hold my reality.”
 
the princesses of ponies were not enough - Once she had discovered the pleasure of twisting and corrupting the bodies of others for her own - she began hunting for other princesses of the world (as well as a few princes). Adding their essence to her ever growing gene pool. Adding their powers to her ever growing mix. The leaders of not just Equestria, but of the world coming together and becoming one.  
Becoming the almighty one.
 
God Empress Cosmos - The undisputed goddess of the Sun and moon. Of harmony, friendship and Love. Goddess and ruler of all dragons, of the highest frozen mountains and of the deepest ocean blue.  
“Now sempai Discord will have no choice but to notice me”
 
Previously  
She got the power of theDragon lord.of the Prince of yak yakistan and of the queen ans princess of The ocean.