Complex sentence: The peryton is a magical beast from the "Dungeons & Dragons" fantasy role-playing game based upon the peryton created and described by Jorge Luis Borges in his "Book of Imaginary Beings".
Split into simpler sentences: The peryton is a magical beast from the "Dungeons & Dragons" fantasy role-playing game. The creature was based upon the peryton created and described by Jorge Luis Borges in his "Book of Imaginary Beings".