In "Macbeth's" final scene, Macduff counters Macbeth's statement that he lives a

charmed life which must not yield/To one of woman born,(V, viii,,12-13)

telling him that the prophesy of the witches that "none of woman born" can harm him will not aid Macbeth since the "angel," (fallen angel, fiend) has not told Macbeth that Macduff

was from his mother's womb/Untimely ripped. (V,viii, 15-16)

When Macbeth hears these words, he realizes that he has met his nemesis since Macduff was not born in natural childbirth.  He tells Macduff that what the witches have prophesied has a double meaning and he has not realized until then what the true meaning is.  Macduff simply tells Macbeth that he is a coward, and forces Macbeth to fight him.  They fight, exiting the stage.  Macduff kills Macbeth, drags him off, and later returns with his head, which he presents to Malcolm

Hail, King! for so htou art: behold, where stands/Th' usurper's cursed head.  The time is free. (V, viii, 54-55)

Once again Shakespeare concludes his drama with the interplay of fate and the tragic flaw of the protagonist.  For, in his lust for power, Macbeth and his fiendish wife succumb to the lure of the prophesies of the witches only to find that their other declaration is, indeed, true:  "Fair is foul, and foul is fair" (I,i, (10),