Hello, Lyshe,
I'm surprised no one has answered you. The cards are using another form of energy the same as the pendulum.  I was an unbeliever the first time I had the cards read for me.  The reading went so well that I started to laugh.  I asked to have another deck used to see if it would be similar.  It was so similar, I started to laugh all over again.  Since that time, I have bought several decks of Oracle cards.  Some of them are about Angels, some about Nature such as trees, some about Guides, some about Saints, etc., etc....   I find if a person is open-minded and allows the cards to fall at their will...  if that is the proper term... then the readings come out pretty accurate.  With cards, there are always several energies at play at the same time. 
Now this is what I have found.  Others may have found a difference in both readings and outcomes.  Mine have always been joyful.

I hope you find your joy and laughter,
Baroness T'ressa

So well said, as always. Sometimes best to wait to hear from people, as this is a slow forum now. I used some of these tools regularly years ago and enjoyed using them.

Whatever it is that you use, it must speak to your heart, so it is always okay to use it for what it brings to you and move on.

For now, after a long life, I prefer to work more on direct communication through other means, and I perceive the tools mentioned as indirect. However, they achieve a lot of nuance for the one who has the ability to listen to them.