Complex sentence: The magical creatures had to flee from our world to save themselves, and the human Druids, the last wielders of white magic, helped them by creating a world suitable for their existence and closing the way there for the human race.
Split into simpler sentences: The magical creatures had to flee from our world to save themselves. And the human Druids, the last wielders of white magic, helped them by creating a world suitable for their existence and sealing the way there for the human race.