Nightmare's Keen Senses
Your other senses come to the fore when your vision fails you.
Grandmaster Training 9,000 gp
You can make a Perception check to locate a hidden enemy as a free action once on your turn.
Power (Augmentable, Psychic) Daily (No Action)
Trigger: You would make a melee attack against a target with partial concealment or superior concealment.
Effect: Your attack ignores concealment.
Augment 1: As above, and you gain combat advantage for this attack.
Published in Dragon Magazine 393.