sub‧consciousness

Somebody told me this, when I was playing tarrot that day :
" you cannot cheat, it's your subconsciousness which controls."
I was shocked.
What will my subconsciousness do? I have no idea.
How can it control the cards?
Is it something evil? Is it something unspeakable?
Why is it 'sub' to my consciousness? Is it because I wear mask in the crowd?

Someone says your subconsciousness flow when you dream,
yea, I do dream a lot.

Imagine yourself is under a hypnosis treatment by psychologist,
what flows in your mind? What comes first?
They may be part of your subconsciousness...