The Saga of the Salem Witch (Agatha Harkness)

When Reed and Sue Richards of the Fantastic Four hire a new nanny for their son, Franklin, they get more than they bargained for in the form of Agatha Harkness - a powerful witch capable of holding her own against the Frightful Four! But Agatha's son, the warlock Nicholas Scratch, may prove to be one of the FF's deadliest foes! Agatha takes the Scarlet Witch under her mystical wing, but the sorceress hides a terrible secret. As a dark prophecy comes true and Earth is terrorized by apocalyptic new villains with horrifying powers, an unlikely team of heroes will form to wage mystical war: Magik, Wolverine, Blade, Spirit Rider and Nico Minoru! And the saga of these Midnight Suns will transform Agatha in unexpected ways!

Collecting FANTASTIC FOUR (1961) #94, #185-186 and #222-223; AVENGERS (1963) #128; and MIDNIGHT SUNS #1-5.