Was thinking of this build for Shadow tanks. Its extremely unorthodox but it might be worth a try. All you do is substitute slow time for the masked assault skill. It allows blackout to be used out of combat and blackout gives 25% damage reduction for 6 seconds. The idea of this build is to give the tank an extra defensive cooldown that he can use up to once a minute. You still get harnessed shadows, but only with project.