I've seen this incantation in action... it works and it works well. At a Samhain ritual in 2003, we were unfortunately harassed by several violent drunk individuals. Our ritual priestess began this simple chant, and as it grew in power, others from the group began to join in. It was amazing. Since then, I've learned the chant myself, and use it whenever I find the need for a banishment.
I was told that this was originally written by someone else (I can't remember who it was!) but that doesn't take away from the power it has.
By the Power of Earth
By the Power of Air
By the Power of Fire
By the Power of Water.
By the Life in the Blood that Liveth.
Be thou ___________ (I usually say "negativity") stopped.
Return thy evil to whence it cometh
Have thy words and deeds returned to thee
As thou would have them be to me
I banish you! So mote it be!
That's all there is to it. Very simple, but oh so effective.
