Agatha Harkness is finally back. After wreaking a bit of havoc and helping bring Wanda Maximoff’s idyllic small-town family life to an end in “WandaVision,” the Marvel Cinematic Universe’s favorite insidious and perfidious witch will take center stage in “Agatha All Along,” a new spinoff series launching Wednesday on Disney+. Agatha’s desire to steal Wanda’s power for herself leads to …
