To elaborate on what Insomnia was saying the law of three is the belief of most magic practicioners of karma. Whatever you do bad to a person will come back three fold (a.k.a three times)
"Ever mind the Rule of Three, three times what thou givest returns to thee, this lesson well, thou must learn, thee only gets what thou dost earn" to be exact it works both ways.
If you play with fire there's no doubt you'll be burned, especially if you're new to magic. So, I would suggest at least going over some white magic before you get down to the nitty gritty.