Today's die of the day is a little different from the rest. Think of it as a single die. This is the d20p-4, the base HackMaster defense die. Roll this one if you are in combat without a shield or any other defense modifiers.
I know this one can be a bit confusing. We are all used to seeing modifiers listed with a + or a -. In this case, think of it as a single die, one we can't produce with plastic.
One thing I have learned since taking up gaming is a lot of math goes on behind the scenes. The numbers you see in the rule books are not chosen at random. A lot of work goes into determining those numbers. Game mechanics has never been my strong point, but I can get behind this die without too many mental acrobatics--and believe me, I did not inherit my father's brilliant engineer's math brain. That I know of. If I did, I'm still waiting for the bad fairy to lift the magic spell that keeps me from using it. :)
Here is a visual aide to help you remember this important Die of the Day, the d20p-4.