I like this prayer I heard from the April 5, 2006 Pre-sanctified Liturgy. It is referred to as a “Prayer behind the Amvon”:

Almighty Master, You created the universe in wisdom. By your ineffable forethought and great goodness, You led us to these sacred days for cleansing of souls and bodies, for subduing passions, and for hope of resurrection. For forty days, You shaped the tablets written with godlike characters for Your servant Moses. Grant also to us, good Lord, to fight the good fight, to finish the course of the fast, to keep the faith whole, to shatter the unseen heads of dragons and to show ourselves victorious over sin, and to arrive blamelessly, without condemnation, to worship also Your holy resurrection. For blessed and glorified is Your honored and magnificent name, of the Father and the Son and the Holy Spirit, now and forever and to the ages of ages. Amen.

This prayer at the dismissal is said before the icon of Christ. Commonly we see dragons in the LXX , and to shatter their heads is a very biblical theme. In the book of Job, in the LXX, the leviathan is ‘the dragon’ literally. It is stated later in the Old Testament in the Prophets that the creatures listed in Job are demonic beings, hence the icon of St. George slaying the dragon.