Task: Question Generation
Input (English): Passage: Earth has been devastated by a nuclear war instigated by five terrorists, and it has taken two million years for the radioactive clouds to once again allow sunlight to reach the surface. Only a handful of humans have survived the apocalypse, while the rest have changed into mutants who roam the radioactive wastelands. Eventually, humanity's true ancestors  – fairies, elves and dwarves – resurfaced and live in the idyllic land of Montagar in peace for three millennia. 
While her people celebrated 3,000 years of peace, their ruler Delia, queen of the fairies, fell into a trance and left the party. Puzzled, the fairies followed her to her home and discover that she has given birth to twin wizards. They were the kindhearted Avatar who spent much of his boyhood entertaining his ailing mother with beautiful visions and his mutated brother Blackwolf, who was pure-evil, never visiting his mother, but spending his time torturing small animals. When Blackwolf learned of their mother's death, he attempted to usurp her leadership, being defeated in duel against a grief-stricken Avatar. Blackwolf left Montagar with a vow to return and "make this a planet where mutants rule".
Years later, Blackwolf has risen to lead the dark land of Scortch, where he and his vast army of goblins, ogres, and mutants salvage and restore ancient technology. He tries to attack Montagar twice, but is foiled both times when his mutant warriors become bored or sidetracked in the midst of battle. Blackwolf then discovers an old projector and reels of Nazi propaganda footage, using his magic to enhance it for psychological warfare: Inspiring his own soldiers while horrifying enemy troops into submission.
Output (English): Who's death caused the twin wizards to duel?