In Julius Caesar, what devices does Antony use in his speech to the mob in order to instigate them against the murderers?
Antony was very masterful in his oration to the crowd. They are very hostile to him as he begins. First, he establishes a common bond. He calls them his friends and countrymen and reminds them that they and he are all Romans. Since they are expecting him to speak against Brutus and Caesar, he disarms them at once by saying he does not come to praise Caesar. In other words, he further neutralizes their hostility. As a persuasive technique, this is refuting an anticipated argument.
The remainder of Antony's speech is masterful persuasion. At various times he uses rhetorical questions framed to make the point he intends to make. He employs anecdote by telling them of the summer night he first saw Caesar wear the cloak which now covers his corpse in the marketplace. He uses strong emotional appeal. He stresses his friendship with Caesar, thus making Caesar a friend, a human being. He plays upon the crowd's greed by raising the facts of Caesar's will. The will also plays upon emotion in that it makes the crowd feel that Caesar cared for them personally. Throwing off Caesar's cloak to reveal his many stab wounds and then reliving the moment of his assassination is also very emotional. Finally, Antony uses verbal irony (sarcasm) in the repetition of the idea that Brutus and the others are such "honorable" men. And, actually, repetition itself is a persuasive technique. Taken together, these persuasive techniques in Antony's skillful hands very effectively turn the crowd against Brutus and the conspirators.