If you plan on writing a protective spell or warning in your BOS, I would say to make sure you do it in a color that is different from the others in your book... If you only write in black, like I do, then it'll be an easy task. I write my warnings in red or orange, not because of any magical color attributes, but because it's a color that draws the eye and makes an immediate impression of warning, and since it's different from everything else, it stands out in memory.
Even without any real magical backing, it'll zing about in their subconscious and could bring about results based on nothing but what -they- believe.
I've found that letting people draw their own conclusions and mete out their own punishments tends to be far more effective than doing anything overt. And why do it yourself when their own minds will make monsters up for you?
~St. Makupuff the Awesome~
"The human race will begin solving it's problems on the day that it ceases taking itself so seriously." – Malaclypse the Younger
The Hell Law says that Hell is reserved exclusively for them that believe in it.
Further, the lowest Rung in Hell is reserved for them that believe in it on the supposition that they'll go there if they don't.
-Holy Book of Truth; The Gospel According to Fred, 3:1 (Principia Discordia)