I definitely want to see a change to dark passenger, but I disagree with your idea Claire as I think this suggestion highlights a problem we already have with dark knight. To mitigate effectively we must give up dps, and when we are already behind in dps I don't think we can spare any.

This is an example of imbalance by design (as opposed to imbalanced tuning), two tanks mitigate party damage and personal damage for free, while another tank must take a dps hit to achieve the same result but lowers its lower damage even further. Having to blow half my mana for a party utility will just highlight this further. I agree with Syzzle, if I'm going to blow half my mana on 1 skill I want it to hurt.