The issue of whether saying "
Flame On!"
is a
requirement for
Johnny Storm to become
the
Human Torch goes to the source of his
powers. Storm, along with his
sister, her
boyfriend, and a
pilot,
blasted off in a rocket ship of the boyfriend's design.
Because of a cosmic storm that the shielding
of the ship was unable to block, the four were
given massive doses of cosmic rays that changed
them into the
Fantastic Four.
The fact that
their powers were derived from science seems
to suggest that there would be no need for
clever phrases and secret words for them
to activate their powers. But remember this
was the golden age of comics and their stories
were written by Kirby and Lee.
The need for battle cries and such were nearly a
requirement. For this reason, the Thing began
the use of his famous line "It's Clobberin' Time!" and
the Torch began to cry "Flame On!" when
he, well, flamed on.
In contrast, heroes like Captain Marvel,
Johnny Thunder, and The Demon all have
powers based completely on magic and therefore
have a mystic phrase or word that must be spoken
before their powers are activated.