When somebody nearby tries to do anything, you can invoke bad luck over him with a Magic point. This costs you no shots. Subtract your Magic from his Action Result. This might very well lead to a botch.
Unluck becomes more expensive as it becomes more unlikely. Each extra use in a sequence costs one additional Magic point; the second use costs two, the third use costs three and so on.
This does not work if his Fortune is higher than your Powers.