Nicol Bolas, The Devastater

This enters the battlefield as a Creature, but Resolves as a Saga after it's Turn Abilities
I: Opponent's Discards 2 cards
II: Look at the top 3 cards of your library then put any Legendary creature onto the battlefield among them.
III: If your opponent's don't control a Legendary permanent, they lose the game
Flying, Trample, Flash