And whats better than one Dancemancer? Two Dancemancers having a Dance-Magic-Dance duel. This makes me laugh just thinking sbout it. Even better when the Dancemancers try to convince the rest of the magic world that Dancemancy is a serious form of Magic. Lol. Adds more meaning to the term, "You Just Got Served!"
This is actually a very simple option mechanically.
Give the mage the Metamagic technique of Centering (Gesture) and make their gesture requirement a dance-oriented move.
This means that:
A) The mage isn't completely useless when NOT dancing
B) Mage is much more effective when they ARE dancing.
In old versions, the Centering metamagic actually required a separate active skill (such as Dance, Keyboard, Latin etc), so this metamagic might fit your thematics quite well
