You want to know which kind of methods as spiritual practice you could use to gain revenge OR to find out who it was?
If you don't know who it was then how do you know he was a "acid satanist" in the first place?
I'm guessing the OP is Italian, here there are some people who call fake Satanists "Satanisti acidi". These fake Satanists believe Satan to be evil, and since they are retarded they worship this fake version of him and they do all kinds of degenerate things in his name. The post here sounds like a troll to me though.