The passage has conveyed that the world is attainable in our time. In this sentence he is appealing the reason for the new world tyranny. Leader and dictators want the world even by crash of bomb. This sentence is expressed as an emotion.
Voldemort thinks that Snape is the master of the elder wand, so the only way for Voldemort to be the master of the elder wand is to kill Snape. He sends Nagaini to kill Snape because he wants the powerful wand all to himself
