I love Korvac and yes he is a Good baddy in the COmics and like Thanos was not the most popular or well known of all the Villains before Avengers Post Credit. But GS Defenders 3 is along the lines of a Poor man's FF Annual 6. Still a Great Book but until it is assured don't be overpaying for a Speculation book that is Tough in High Grade....That being said, I have 2 Copies but 1 belongs in my Set (Finishing whole defenders Run). A Key in the Korvac Saga is the Avengers books that Transcend the One Character. I still think Kang, Annihilus, Galactus, Doom and Mephisto would be more in line as a Major Phase 4 Villain. HOWEVER being part of the Badoon (Baddy Skrulls) it may seem more in line for a Cap Marvel Villain so basically if you love SPEC this is a No Brainer (and a Good Story to boot)