Mandala comes from 西藏密宗. Mandala is a picture where the top and bottom, left and right are the total reflection of each other, and the picture is coloured in red, blue, green and orange.
How it works is: look at the Mandala card for 5 seconds, then close your eyes for 5 seconds. When you eyes are closed, try to let the image of the Mandala card you see stay in your mind. Repeat the steps several times. This practise is believed to be able to stimulate the right brain. And it’s advised that the practise needs to be carried out consistently for at least 3 months.