The double spades effect

Don't try to bluff
I'm wearing these shades
I anticipate the moves that you make
I'm calling you now
I'm watching you sweat
I'm shaking you down
If I were your friend, well, I'd hit you now
I must stay ahead
I'm checking the scores, beginning to end
It's you who shouts more
But me who has led
Yet you're shouting more
We'll come to the end, and I'll lose this war
Oh you've changed the law
Yes you've changed the law
Less is more