I don't really subscribe to a god, but there have been times in great turmoil where I have said a little prayer to something just because it made me feel better for a short amount of time. A spirtual 'popper', as it were.
So, I got to thinking, if prayer can 'work', why can't it work to influence bad outcomes also? So, when I had a difficult breakup, I prayed that my ex-girlfriend would get AIDS or Hep-C. I came to find out that she contracted chlamydia through a mutual friend a year later. Close enough.
Then a few years later, after I got married, my wife was having a difficult time with a co-worker of hers. So on a lark, I would say some silent prayers wishing that this woman would get cancer or have heart disease. Then she DID get cancer. She had to quit her job to recover and never returned to work.
I was pretty freaked out about it and never touched my dark magical powers again.