Holy Bovine
First Post
The DM should be honour-bound to allow it, simply because it would mean your PC got to wear an awesome hat. Take a look at any of the pictures of Dark Sun NPCs (City State of Tyr is a great example, as are any pictures by Baxa) - 90% of them are wearing totally outrageous hats. The beholder-cultist hat would fit right in. Your PC would be the talk of the town based on his hat alone.
For this reason alone I'm allowing this in the OPs campaign regardless of what his actual DM says.
