I agree 100% with this assessment "Now, Harbinger was decided to be the opposite of that. Your shroud, still with deadly skills that can kill an enemy quickly, now no longer protects you, in fact, it harms you while you stay in it. "
I think it would have been a good mechanic to consume 1 stack of blight for 1% DS increase per interval (or 1 stack of a boon) while in Harbinger shroud or something. It gives you a reason to build blight and then a way to rid yourself of it.