"So mote it be" is a ritual phrase used by Freemasons, in Rosicrucianism, and more recently by Neopagans. It means "so may it be",or "so must it be", and may be said at the end of a prayer in a similar way to "amen". The phrase appears in the Halliwell or Regius Manuscript, the earliest known document relating to a society of Masons in England dating from the first half of the 15th Century. " Amen! amen! so mot hyt be! Say we so all per charyté".
The phrase has been taken up by neopagans and they use it in a similar way in their ceremonies and rituals.