“Cause I...
I'm capable of anything
Of anything
& everything”

Katy Perry – Dark Horse Lyrics on LyricsMode
She is warning the guy not to mess up or he will feel her wrath.
She can attack you at anytime no limits and once she gets you it is the end of you that is my Katy Perry don't judge and don't hate on her or else she has my back well everybody's back but and she will use her Egyptian powers on you never to let you attack her again so don't be unpleasant around Katy Perry got it play no game no fame.
Katy Perry is saying she is capable of everything and she doesn't want anybody to mess with her or she'll use her Greek mythology powers (because Aphrodite is the Greek goddess of love and beauty) or else she'll use charm speak and have them do what ever she wants them to do.