TL;DR: In mythic BoD, a mythic-geared DH can expect roughly an 8.0-8.5% reduction in damage taken while DS is down, and a 0.0-0.5% reduction while DS is up. Average damage taken is dropping by roughly 6.5%. This isn’t really going to do much for us. It can be thought of as essentially equivalent to the benefits of Void Reaver.