What you need:
12" string
Scissors
A small fire

Tie a knot at both ends of the string, then say, ''Seeds of discord now be sown. Dissension be your thorn and flower. Engender severance when you're grown. Division come within your power. Their love begins to dissipate like smoke. Their time together draws toward the ed. They grow apart like lightning cloven oak. A breach that's impossible to mend.''

Cut the string in half, then throw it in to a fire.