I am not Catholic, and I refuse to vote for a Mormon. That said, I still maintain that your ritual in the original post is ungodly (it bears a striking similarity to voodoo), and I therefore refuse to participate in it.
I do, however, want to apologize for misinterpreting the intent of your post. When you mentioned stabbing a picture of Romney with a knife, I just assumed that it was calling death upon Romney. Thank you for clearing it up.
Here's my way of praying for the defeat of evil (another Old Testament prayer):
"Rise up, O Lord! May Your enemies be scattered, and may Your foes flee before You."
I think you're on the right track (spiritual warfare, IMO, is too often overlooked), but I think you're going about it the wrong way (shamanistic rituals which target people, rather than the spiritual Enemy behind them).