My ideas I have had reading all ppl thoughts.
Shadow all 3 min CD would be OK if it reflect back some kind of debut to boss example magic defence down. Why magic defence and not physical is to avoid it being used as berserk for self buff rather as raid synergy utility.

Other skill that could work whit that kind of change would be da dark passenger change blind effect to something that all so work in raids and benefit party not just you. If pld is defective utility tank then drk would be offensive utility tank. Whit our lack of defence it fits