A 15th Century Game of Whodunnit!
Macbeth must have wanted to be king even before encountering the witches, otherwise their predictions wouldn't have had such an immediate effect on him. One of the first things he does after learning that he will be king is write to his wife, telling her that she will be queen one day. Her immediate response is to say that Duncan will die under their roof, and her next lines only further support the fact that she wants Duncan dead, "Come, you spirits that tend on mortal thoughts, unsex me here, and fill me, from the crown to the toe, top-full of direst cruelty! Make think my blood; stop up the access and passage to remorse, that no compunctious visitings of nature shake my fell purpose nor keep peace between the effect and it! Come to my woman's breast's and take my milk for gall, you murd'ring ministers, wherever in your sightless substances you wait on nature's mischief!" (1.5.46-56). Basically what this means is that she wants evil spirits to make her strong enough to handle murdering someone.
Once Macbeth arrives, she quickly tells him about how she wants to murder Duncan. Macbeth, however, is uncertain on whether this is a wise decision or not. He tells her that they will talk about it later. In the next scene, Lady Macbeth puts on a great pokerface, communicating with Duncan like she wasn't just planning to murder him, "All our service in every point twice done, and then done double, were poor and single business to contend against those honors deep and broad wherewith your majesty loads our house. For those of old, and the late dignities heaped up to the, we rest your hermits" (1.6.17-23). In this line, Lady Macbeth is saying that nothing she or her husband can do will match how generous King Duncan is.
Then, in the preceding scene, Macbeth expresses his apprehension to his wife, only to be shot down and insulted by her, "Was the hope drunk wherein you dressed yourself? Hath it slept since? And wakes it now to look so green and place at what it did so freely? From this time such I account thy love. Art thou afeard to be the same in thine own act and valor as thou art in desire? Wouldst thou have that and live a coward in thine own esteem, letting "I dare not" wait upon "I would," like the poor cat i' the adage?" What this all means is that she is calling Macbeth's ambition to be king drunk and hungover, and then she criticizes Macbeth's weakened resolve to get the crown, calling him a coward. She compares him to a cat in a proverb who wouldn't catch fish because it was afraid of getting it's feet wet.
The first literary device is comic relief. In Act 2, Scene 3, there is a knock at the door. The man who answers just so happens to be drunk. Before opening the door, the drunken porter rambles on about the knocking, saying, "Knock, knock! Who's there, in the other devil's name?... Knock, knock, knock! Who's there? Faith, here's an English tailor come hither for stealing out of a French hose.... Knock, knock! Never at quiet! What are you?" (2.3.7, 11-13, 15). This is an example comic relief because the porter takes a very long time before he opens the door, wondering what on Earth that knocking could be.
My second literary device is imagery. In Act 3, Scene 5, Hecate and the Witches meet. Hecate begins answering the witches' questions, then says this, "Upon the corner of the moon there hangs a vap'rous drop profound. I'll catch it ere it come to the ground; And that, distilled by magic sleights, shall raise such artificial sprites as by the strength of their illusion shall draw him on to his confusion" (3.5.23-29). What Hecate is saying in this line is that she will acquire a magical drop from the moon, treat it with secret art, and create spirits that will lead Macbeth to his destruction. This is an example of imagery because she says she will take a drop from the moon, putting the image of something coming off the moon in readers' heads.
The third literary device I have is verbal. In Act 2, Scene 3, Macbeth says, "Had I but died an hour before this chance, I had lived a blessed time..." (2.5.103-104). This is ironic because Macbeth is talking about himself dying, then he ends up dying at the very end of the play.