Weapon of Earth - Pentacle, How to construct the earth pentacle Options

I'm building an earth pentacle to use in my rituals, but i have some doubts on its creation.

I'm building it around 6 inches, out of some wood boards i glued together.

I read in "Modern Magick" by "Kraig" that it is better to be concave, because this would direct the energy directly back to the one who sent it, in case of an attack.

I really don't agree to that, as i don't see how anything reflects back to its origin on something concave differently from something flat. I also don't understand why it has to be used against attacks, as it is obviously meant as a defensive weapon, or a shield. And a shield is definitely not concave, more the opposite.
It just doesn't add up, Kraig's theory, and it leaves me confused...

Could anyone give me some advise on this.
Also, the origin of the god names that are meant to go around it are not given in Kraig's book, I would like to know them to. (IMG:style_emoticons/default/huh.gif)

Bear in mind there are a lot of different systems of correspondences out there. What I use is Golden Dawn standard, which has influenced most of the other ones so I guess that is the one you are interested in.

Check Regardie's Golden Dawn and I know they are in the Cicero Self-Initiation book but are organized by grade instead all in one place. So if you wanted the ones for air look in the 2=9 grade material and they are in list form. The same goes for Regardie's Golden Dawn.