Modernly, "evoe" has been somewhat purloioned by neo-mystic groups like Wiccans because it is fancied as a special phrase for invoking high mystic something-or-others. In traditional Green drama it is used as an invocation of Dionysius, the goat-god of the Bacchanale. From Antigone:

Brightest of all the orbs that breathe forth light,
     Authentic son of Zeus, immortal king,
Leader of all the voices of the night,
     Come, and thy train of Thyiads with thee bring,
          Thy maddened rout
Who dance before thee all night long, and shout,
          Thy handmaids we,
          Evoe, Evoe!