Over the decades, Doctor Who has introduced a complex web of lore, including weapons like the Moment that need a little more explanation than is generally given. When the series was revived by Russell T. Davies in 2005, a critical addition to the Doctor's backstory was that Gallifrey had been destroyed by the Doctor's hand in an attempt to stop the Time War and eliminate the Daleks. However, the question of how the Doctor managed such a massive task was left unanswered until the 50th Anniversary special, "The Day of the Doctor," when viewers finally got a glimpse at the Doctor's darkest day.
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