When Baffling End enters the battlefield, exile target creature an opponent controls with mana value 3 or less. When Baffling End leaves the battlefield, target opponent creates a 3/3 green Dinosaur creature token with trample.
In a multiplayer game, the target opponent who creates a Dinosaur token doesn't have to be the same one whose creature was exiled.
While Baffling End's two abilities are flavorfully related, they are independent. If the first ability doesn't resolve (perhaps because the target gained hexproof), the second will still create a Dinosaur token when Baffling End leaves the battlefield.