Who influences Macbeth the most in Shakespeare's tragedy Macbeth?

According to renowned Shakespearean critic Harold Bloom, Macbeth is most deeply influenced by his imagination, as he terms the play "a tragedy of the imagination."

Because of its numerous murders, this play becomes a virtual tragedy of blood, but Bloom contends it becomes even more horrific because of the "ultimate implications of Macbeth's imagination itself being bloody":

The usurper Macbeth moves in a consistent phantasmagoria of blood: blood is the prime constituent of his imagination. He sees that what opposes him is blood in one aspect...and that this opposing force thrusts him into shedding more blood. (Shakespeare: The Invention of the Human) 

Macbeth himself says, "It will have blood, they say: blood will have blood" (Act II, Scene 4, line 128). That is, Macbeth imagines the blood he has shed will return to avenge itself by killing him. Thus, his mind becomes consumed by these horrible imaginings of this continuing battle of blood.
This concept is suggested in Macbeth's soliloquy of Act II in which he imagines the bloody dagger that is suspended in front of him before he kills King Duncan:

Mine eyes are made the fools o' th' other senses,
                                             ....I see thee still;
And on thy blade and dudgeon gouts of blood
....It is the bloody business which informs 
Thus to mine eyes. (Act II, Scene 2, lines 52-57)

Throughout the play, the word blood in its various forms is repeatedly used by Macbeth and later even by his wife, Lady Macbeth, who imagines that she cannot wash away the blood of Duncan that has fallen upon the steps of their castle.

In his plan to have Banquo and his son killed in Act III because of his fears about the witches' predictions that Banquo's sons will be kings, Macbeth tells the two murderers that Banquo is his enemy "in such bloody distance [disagreement]." Moreover, in this act there is imagery of turmoil, suspicion, and paranoia. This is because the further Macbeth involves himself with bloodshed, the more violent, bloody, and horrified he becomes. "[T]here is no power of the mind over the universe of death," Bloom writes, and this bloody path continues until Macbeth's mind finally succumbs to all its terrifying imaginings when he perceives "Birnam Forest come to Dunsinane," just as the witches have predicted, and he goes to meet his end.

Macbeth's tragedy is his complete yielding to his ambitious, bloody imagination. For, as Bloom contends, the witches have placed nothing in Macbeth's mind that has not already been there. Indeed, from the beginning, Macbeth proves himself a bloody killer in his battle with Macdonwald. With their preternatural powers, the "three sisters" identify Macbeth's terrible imagination, and merely spur his mind further with their predictions.