Given the current news about WotC trying to de-authorize the OGL 1.0a, we’d like to point out that Ebon Fantasy Essence’s text can be used under the Creative Commons CC-BY-SA 4.0 license. Since that license actually contains a statement saying it is irrevocable, you don’t have to worry that someday we might be under new management that decides to pull the rug out from under you!
We also offer OGL 1.0a licensing, but since Ebon Fantasy Essence itself contains no copyrightable material taken from any other OGL product, we will not have to rewrite anything even if the OGL 1.0a should go away.