This meditation helps to awaken the kundalini. It can be used before any ritual to add power to it and tune your consciousness to the spiritual dimensions.
Visualize a fiery serpent coiled in your root chakra (between the anus and the genitals). See it setting the area on fire. You visualize flames burning on it. After some seconds, visualize the serpent climbing through your spine and setting each chakra on fire (the second chakra is located below your bellybutton; the third is in the stomach area; the fourth, on the chest; the fifth, on the throat; the sixth, between your eyebrows; the seventh, on the top of your head).
When you finish, visualize your whole being on fire. Focus on the energy within and around you, and proceed to the ritual.