I'm assuming that you are referring to Gabon (often Gaboon) Ebony, which tends to receive a lot of bad press in relation to cracking. I have turned SEVERAL DOZEN duck calls from this "true ebony" and roughly 10-15 pens. Heat is your enemy but I've never had one crack... not one blank. When drilling and turning, sharp bits and tools are a must, and light cuts are paramount. Don't use CA while turning, it generates heat when flashing and can be problematic. Turn as normal, maintaining a very light, cool touch. Sand to 2000, again watching the heat buildup. Upon completion of sanding, finish with Medium CA. It will adhere without soaking in and generates less heat than thin.
Duck calls are used in the worst possible cold and wet conditions then haphazardly tossed on a toasty dashboard yet I have not had a single call returned.