Blindfight: won't caught flatfooted by invisible melee attackers, immune to gaze attack.
Blindfight,Imp: won't caught flatfooted by invisible melee/range attackers in 30 ft, reroll once if melee attack missed because concealment, ignore partial concealment in melee.
Blindfight,G: won't caught flatfooted by invisible attackers, reroll once if melee attack missed because concealment, ignore partial concealment and treat total concealment(50%) as partial(20%) in melee.
Blindsense: ignore all invisibility and concealment in certain radius.
Tremorsense: blindsense in 30 ft, immune to gaze attack.
Blindsight, 60 ft: blindsense in 60 ft, immune to gaze attack.
Echolocation: blindsense in 40 ft, immune to gaze attack.
Blindsense from dragon disciple: blindsense in 25 ft, not immune to gaze attack.
Improved Precise Shot: ignore partial concealment, range attack only.