The Shadow is very straight forward. Go for melee damage and power damage and she decimate targets (Shadow Strike benefits from both melee damage buffs and power damage buffs). Juggernaut shield is a great Gear to use on her, then you use Bonus Power tactical cloak (with duration) to get off two Shadow Strikes per Tactical Cloak.
It usually is enough to do heavy damage, but Shield gate might be a tad frustrating. :P