A supposed friend who I have helped rise through the ranks o a company has recently spread lies and bullshit about me in the company to new and nearly new people to the point where one person working closely with me resigned for no reason, when I met her a few days later she told me what this guy had said an has since given me a statement

This guy I promoted thru the ranks and is now on 60k a year and in an audi purely on my recommendation an has enjoyed many overseas trips

He is good at what he does but was deffo lifted by me and our supposed friendship

I'm looking for a sneaky yet effective way of fucking him over without him knowing or with him knowing and not being able to prove it

Any ideas?