Zen Marksman

A true master need not see his target for his missiles to fly true. With this schtick you can ignore modifiers for visibility, obstructions et al. You can shoot in complete darkness, at invisible opponents or through thick fog or nauseous fumes with no penalty, though you must know they are there and can still stumble when groping around in the dark.

You can ignore Cover & Concealment as long as you could conceivably shoot through it; you can ignore interior walls but not concrete walls, living creatures or armor plate.