Ring of Blades (Complete Arcane) spell?

[Shape D.]

But then wouldn't it be a "sphere" of blades.

 

[Nonlethal Force]

Yes, it's a bit confusing because it says "horizontal ring" and "all adjacent square" may be you have a small "rotor" of blade on the head?

Well, I was assuming that when the spell description was written it was done so without thinking 3D. Most combat occurs on the ground, where one only need worry about 8 squares around you. So that would be all adjacent.

But as a DM, because the book specifically says horizontal ring, I would allow attacks from the square immediately above and immediately below.