A reference to the card game known as "Spades" -- where the spade suit is the deck's most powerful -- this line is suggesting that MCs lacking any power moves (metaphorically, "spades") should just give up.
you can call me Caesar is probably famed Roman emperor Julius Caesar, it makes sense that billionaire HOVA would identify with him. Could also be labor organizer César Chavez, since Jay has helped out so many young talents. I think CZAR is an automobile??