How does shakespeare bring a sense of supernatural and evil in act 3 scene 2 ?(Macbeth)?

i need to answer, by talking about use of ghosts/witches/hallucinations..etc portrayal of character and how this scene relates to the rest of the play.(this is the scene where lady macbeth tries to comfort macbeth when he is thinking about banquo and fleance. he realises he needs to kill them. he will kill anyone in his way.) thanks very much for the help!