I am planning on writing a short adventure called Valley of the Umber Hulks but I have a question about the open gaming license. I believe that Umber Hulks are one of the monsters that do not fall under the OGL as they are considered to be an icon of the D&D system. Does this mean that I am not allowed to use them in an adventure created for another system, let's say Labyrinth Lord? If I only plan to distribute the adventure free of charge does this change anything?
I'm a little confused on how this would work, any help figuring this out would be much appreciated!
