That would be Force stealth (which I will cover). It allows a Force user to hide their alignment or even their presence from other Force users.
Query: What is the technique that Sidious used to mask his dark side presence from the Jedi Order?
And thanks for doing my request.
I am planning on doing Sith magic soon as well. Probably along with Darth Malak.
Edit: I do believe Force stealth is another one of Traya's powers.