DCI Level 2 Judge
"That's what's so stupid about the whole magic thing, you know," Rincewind said. "You spend twenty years learning the spell that makes nude virgins appear in your bedroom, and then you're so poisoned by quicksilver fumes and half-blind from reading old grimoires that you can't remember what happens next."
- Terry Pratchett, The Colour Of Magic
This "has" doesn't mean "owns, possesses".
What the card is trying to say is: Any player may allow Book Burning deal 6 damage to him or her. If no player allows this, Book Burning makes the targeted player put the top 6 cards from the library into the graveyard.