Discuss the efficacy of Iagos plan.

Iago's plan really only works by the destruction of other characters. I think his plan is efficient because Iago is a master manipulator. In lesser hands the plan might fall apart. Iago understands Othello well. He understands that the mere mention of "cuckold" will get Othello's obsessive mind feeding upon imagined jealousies. Iago knows how to gain the confidences of people like Rederigo and Cassio only to betray them without them even knowing it.