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In Harry Potter, the fact that "The wand chooses the wizard" becomes a main plot point. Wands will not work for you properly if they either didn't choose you, or if you didn't win them in battle. But in The Deathly Hallows, after escaping from Malfoy Manor, Ollivander crafts and sends Luna a new wand by Owl Post as a thank you for helping keep him alive while imprisoned. Luna appears to have no problem wielding the wand, yet she neither won it, nor, it seems, was she chosen by it. So how does it work for her?