For the novice, please use divination before attempting.
Get into a deep meditative trance visualize and feel your energy body, turn your consciousness to your strongest energy center. Imagine yourself expanding, growing larger and more powerful with every second. Call upon the four winds, the four corners, the gatekeepers, whatever you use.
Now see and feel a massive black hand with claws of darkness reaching out of your energy body. Fill it with all the hatred and malice of all your combined past lives and future incarnations.
Now feel the heart beat of your enemy. Gaze at their heart, see how it moves energy throughout their organs. Increase your sight down to the molecular level of their being and then some. Keep this in your sight.
Reach the black hand out to them and grab their heart. Pull it out of their body.
Now you have a few options. You can spit on it, representing the snake, this will bring a slow and painful death. Or you can drain all the power out of it and replace it with negative energy. Remember follow your intuition, get creative with it. Good luck and happy hunting