I'd like to warn somebody of one of their harmful managers, or even a so-called fake friend, so I say it like this:
Don't trust him! He is nothing but a cunning person who is trying to harm you/put you down, with his special ability , so gradually, *smoothly,softly, wisely, and, secretly* via a pre-planned plot that you won't even notice or suspect his intentions.
What idiom, phrase, term, ... could be used for describing this wise person/ fake friend/whatever you name it, -or his ability-*while focusing on using his wisdom for doing his hidden harmful actions smoothly!
P.S 1: I have found "back-stabber"; "two-faced"; "a snake in the grass"; "a wolf in sheep's clothing"; but none of them cover all those attributes as a whole.
-(there is an idiom in my country which says" Don't trust him! He cuts off the throats/ heads with cotton!) -( these people are potentially good politicians!, so you can use this idiom even for countries or politicians who achieve their goals by acting in this way!)
Note: my question has been marked as "duplicate", but the answer I'm looking for, has nothing to do with answer which user87131 is looking for, he/she is focusing on a liar fake friend, and me, on some other attributes and actually maybe this person is not necessarily a friend, maybe he is someone whom I am obliged to deal with,!!. Please reopen my question, if possible! -(Sorry, Everybody! I had to edit my question!)
P.S2: I just found these political terms: "Soft War", "soft power"! And both can totally convey the meaning I am looking for, so Can I use them In non-political cases, too? , Like: , "Don't trust him, he is good at soft war!/ he is good at applying soft power"?