Fantastic Four, Vol. 1 #312 (1988)

The Fall of the Mutants - The Turning Point!
Sharon is having a very difficult time coping with her transformation, and the Thing isn't sure how to help her. Add in the presence of Dr. Doom, asking the Black Panther for help retaking Latveria, and throw in an attack on a parade in honour of X-Factor, and you have a recipe for a major battle.
Release Date: 1988