I would like to learn brutal terms, words not known by much people that represents extremely nefarious things

Probably nobody knows. If you are asking us this question because you think you're "evil", you're mistaken because we're not. We are not interested in "nefarious things", and Satan and the Gods are positive beings.

Use a dictionary and/or thesaurus.

This has nothing to do with Satanism btw.

This is a very childish thing. Nobody is impressed by you knowing a rude word.