Three items that give mastery over death:
1) The elderwand: wins any duel. Stolen from German wand maker guy by Grindlewald. Taken from Grindlewald by Dumbledore. Taken by from Dumbledore's grave by Voldemort. Voldemort mistakenly believes that the wand's rightful owner is Snape, because he killed Dumbledore, which cases Voldemort to murder Snape. Harry declares the rightful owner of the wand is Draco Malfoy, who's wand he stole, and thus the true owner is Harry Potter. Harry uses the wand to repair his own wand and returns it to the grave of Albus Dumbledore.
2) The stone of Marvolo's ring: allows one to commune with the dead. Also enchanted to be one of the horcruxes of Voldemort. Fatally wounds Albus Dumbledore, who tires to use the ring to commune with his dead mother, father and sister. Willed to Harry Potter by Albus Dumbledore, hidden inside a golden snitch to conceal it from the Ministry of Magic.
3) The invisibility cloak: uh you should know what that does by now