Complex sentence: His Nimbus 2000 is destroyed by the Whomping Willow in "Harry Potter and the Prisoner of Azkaban" and his Firebolt is lost in "Harry Potter and the Deathly Hallows".
Split into simpler sentences: His Nimbus 2000 had been destroyed by the Whomping Willow in "Harry Potter and the Prisoner of Azkaban". His Firebolt had been lost in "Harry Potter and the Deathly Hallows".