While this issue features the "Secret Origin of Dr. Fate!" the real reason it's a Copper Age key is because it has a Todd McFarlane cover and contains some of his earliest work.  It's a must for Todd McFarlane collectors.  This book is graded 9.8 NM/MT with white pages by CGC.  It has nice alignment, beautiful color, and gloss.  There is a pretty low population count of this book in the CGC census, with only 51 copies graded 9.8 and 216 total graded copies as of this listing.