Metaphor: "I lit a fire just to feel something" compares the desire for intense emotion to the act of setting something on fire.
Personification: "These waves can wash away my sanity" attributes human-like qualities to waves.
Simile: "I'd tear down my empire for my love, she won't play games or pretend" compares the singer's willingness to sacrifice everything for love to tearing down an empire.
Alliteration: "We'll be the brave, we'll be the last, we'll be forever," repetition of the "b" sound creates emphasis and adds to the emotional impact of the lyrics.
Repetition: The repetitive use of the word "grenade" throughout the song creates a sense of urgency and desperation.