Original: To defeat Harry, Voldemort steals the most powerful wand ever created, the Elder Wand, from Dumbledore's tomb and twice casts the Killing Curse on Harry with it.
Simplified: To defeat Harry, Voldemort steals the Elder Wand from Dumbledore's tomb. It is the most powerful wand ever created, and he twice casts the Killing Curse on Harry with it.