First you must can use negative energy,and have psi sword,and this technique not for beginner
Psi Sword Hold out your hand and close your hand enough so it looks like you're holding something small such as one of those bats for little kids. Now pull psi from your third eye by visualization and make it flow down your arm and into your hand forming a sword. The more energy you add to it the stronger the sword will be. Try stabbing something with the sword and program it to stay in the object and not to fade away or dissipate, then try pulling the sword out.=====Negative Energy Summon=====
To use negative energy, you need to learn how to summon it first. Feel out the Psi in your body. Now begin to think of feelings that strongly anger you. Also think of things of evil (demons, vampires, etc...). Now picture all those thoughts spreading out of your mind and creating a coat around your body. Now use the Psi Flame technique so that your Psi has to pass through the coating. As it does, picture the coating changing the colour of your Psi to a dark purple or blue. You have summoned negative energy
And use your negative energy and imagine it form a mask in your face do it until u feel something,I don't know what will you feel,I just write what do I want to write.and I'm still a beginner please help me.