All students of magic know his name: Starswirl the Bearded, great prodigy of spellcasting and personal student to Princess Celestia. The academic community owes his legacy an enormous debt, as do all students of higher-level magic.

Very few ponies know that Starswirl the Bearded was also history's greatest and most important failure.

The so-called Destiny Spell was the culmination of Starswirl's entire life's work. It was the greatest spell that he ever cast--and it was also the last spell that he ever cast.

Warning, comments contain major spoilers.