It isn't from and official books, that would be too easy
I read in a 3rd party book, a class I thought was called The Logicer, but I've been unable to find it since I read it that one time (I swear I did not dream this up).
In effect, anything that wasn't part of the natural world and couldn't be found or built by normal hands, he would disbelieve it. His disbelief would actually be an ATTACK against the "monster".
Example: So, we enter a chamber with a beholder. Beholders are Aberrations, and not naturally occurring. The Logicer would spout out how a creature could not fly on it's own nor does it have the proper space for a digestive track....if he succeeded in his "attack" then the creature would take damage. In the following round, he could follow it up by saying that even if he had a digestive track, he sees no means for expelling waste materials from it's body. Another attack would ensue.
I think you get the point, and I would absolutely love to find this prestige class again. Could anyone help me please?
Thanks in advance,
Shalandar