when sending grey energy do I also need to visualise grey energy infused into all the chakra of my enemy or just infusing grey energy only with aura of my enemy is enough?
Sending the energy to their aura is standard, but if you want to be as destructive as possible, visualizing the energy seeping into every aspect of their soul is the way to do it. So yeah: chakras, aura, light body; their mind and consciousness; also material visualizations like their brain and body decaying.
Just be careful, this is super destructive and if you just want a fair outcome of justice, sending the energy to their aura and chakras is good enough.
If this individual is a Jew, than it will only empower them. You should do justice under the Gods. Ask for help. Do you think you are advanced enough? this is intermediate-advanced practice.
You can do the destruction ritual which you can find on JoS, as a beginner.